Tuesday, January 12, 2021

next council meeting

I heard through the grapevine there's a RASC Toronto Centre council meeting planned for 28 January...

Monday, January 11, 2021

it slumps

Right! 

While reviewing Night Watch by Dickinson, while reading (skimming really) about the Moon, I spotted this on page 139:

There may once have been such [impressive tall] peaks on the Moon, but millions of years of impacting debris has hammered them down.  In addition, the lunar surface material, which is comparable to lumpy garden dirt, tends to slump over time.

It's lumpy on the Moon I guess.

Sunday, January 10, 2021

another vertical stack

I like this more.

Another "folded" design. Almost the same volume as the previous... 460 000.

Both counter-weights at the bottom and in the same orientation. Maybe that's silly. But I do think from a usability perspective, it will be better. Load the counter-weights first, either way, doesn't matter.

another mount layout with voids shown

I think the balance will be OK.

I was thinking about this with the previous design: inserts, miniature boxes, designated for specific bits. Light-weight cardboard boxes maybe? So insert the mini-box overtop the weights.

I see pre-fab, integrated compartments for the shaft and HD. Slide 'em in.

At the bottom of the box, a wedge to support the mount at the bottom. A U-shape cradle will be opposite to support the RA housing. I rather like this, for taking the weight of the mount, but with a non-moving part.

No strange gymnastics to insert the mount into the case...

Lots of space atop the mount for bits and bobs.

Reminds me of the Questar 3½ vertical case...

continued case design

OK. I think I have a potential good case. I put aside research on case building and joinery using plywood using hand tools...

It did work, as I expected. Doing a detailed model in 3D let me play with the spaces in three dimensions and "look" for voids to put bits and pieces. I tried an approach where the mount is stored in a "folded" configuration, not inline. Immediately, it suggests a smaller, tighter space. The counter-weight shaft surprisingly put a significant demand on the overall form factor.

It looks fairly compact, in terms of volume. A little wider than I wanted but it works.

Continue the measured approach, in old 123D, working on the declination bits today. Deliberately put the counter-weights low, and at opposite corners, for weight distribution and balance.

mount case layout with voids

Looked up, from my packing list, all the bits I need to cargo about...

Now I have to figure out how to "load" it.

From 123D, the total volume is 448 800 mm2.

avoiding a website

Ignoring Live Science. Poor quality. The web site looks like it's pushing hokem and trying to generate views/hits when they don't really know what's relevant.

made a volume

Made a volumetric space to help in the custom case design for the Vixen Super Polaris (with GoToStar system). But I realised this monolithic piece will not allow me to bend and fold the mount. And I, somehow, have a feeling that a folded configuration might be the way to go...

case design inline 1

Trying to get the heavy bits to the bottom...

A lot of wasted space...

Volume: 782 302 mm^2.

Saturday, January 09, 2021

checked GRS

Checked the Great Red Spot positioning in various software apps.

SkyTools 3 Pro - correct.

Stellarium 0.20.4 - wrong.

Chris had told me about this... the newest version did not fix the GRS position.

SkySafari Basic for Android - wrong.

I was hoping the latest update for SS-B would fix this. Nope... I'm increasingly dissatisfied with SkySafari. The app, the way the company does promotions, they way they communicate with their user community.

Stellarium (free) for Android - wrong.

Corroborated all this against Sky & Tel and JUPOS.

helped observer again

Helped Hugues again. He had viewed HD 21700 in his C14, sketched the view, but was confused. There was a nearby tight double. He had questions about the magnitude values I had quoted. I double-checked my values and computed the combined magnitude of nearby STF 401. I think all my data was OK. Reminded him that some of the doubles, in his "big gun" will be widely separated.

it's easy

Learned it's pretty easy to assign a keyboard shortcut to a script on Stellarium. Told Chris.

This pertains to his query about zoom to a 30 degree field. It can be done with the script console with a direct command but it's clunky and not practically in a presentation with humans watching. But if one makes a script, it is easy to invoke it.

classic computer programming

Now, some weirdness ensued. The Ctrl + number or Alt + number keyboard shortcuts were not tolerated. Why?! Stupid that it is not explained...

I used, in the end, simply 3.

white skies

Clouded out. I wanted to view Mercury, Jupiter, and Saturn from "the hill," from my local water tower/reservoir. Was ready to hick to the school with camera, tripod, and binos. No joy. Wispy clouds everywhere.

Friday, January 08, 2021

learned new way to set FOV

Chris V pinged me and asked if there was a way in Stellarium to get to a specific zoom level or field of view size.

I said, "Yes," thinking of the old script method I had discovered many moons ago. But I'd have to look it up...

Then I remembered the keyboard shortcuts, Ctrl+Alt+1, Ctrl+Alt+2, Ctrl+Alt+3, etc.

Chris said the shortcuts didn't work as he wanted to get to a 30° FOV.

Ctrl+Alt+4 shows 45; Ctrl+Alt+5 shows 20. Big jump.

So I renewed my search efforts. Found my note from 2006 (!) using Stellarium 0.9.x. Back then, you could use the Script Commander text box (after editing an INI). Then you could type a text command for zooming and specify the field diameter in degrees.

In my modern Stellarium on my Win10 desktop, I activated the Text User Interface but it didn't seem right.

So I tried the Script Console. Typed the old command but that threw an error.

Dove into on online manual and looked up the script command. 

StelMovementMgr.zoomTo(size[,speed]);

where 

  • size is in degrees, and; 
  • speed is in seconds, optional.

The semicolon is likely important.

Typed stelmovementmgr.zoomto(30); into the Script Console panel but it didn't work. Huh?

Made a script SSC file, copied the appropriate command from the manual, stored it in the YOURDRIVE \Users \YOURUSER \AppData \Roaming \Stellarium \scripts folder, ran it, and it worked. Thirty degree field. A little clunky...

Told Chris.

Shutdown Stellarium, took a break, then tried it again.

  1. access the Script Console by pressing F12
  2. ensure the Script tab is active
  3. enter the command StelMovementMgr.zoomTo(30);
  4. click/tap the run script (triangle-play) button
  5. close the console window

That's easy and quick!

Warning! Stellarium script commands are case-sensitive!

By the way, you know you're entering valid commands in the console when they change colour...

§

All this got me wondering if you can assign a keyboard shortcut to run a particular script...

spotted Jupiter (Bradford)

After the colourful sunset, I spotted a planet on my own, without my specs, in the south-west, very low. Pointed it out to rho. I supposed it was Jupiter. I short time later, I fired up SkySafari. Yep, Jupiter was highest. Oh, Mercury wasn't far away. It would be impressive... Tomorrow and the next night very good!

nothing done (Bradford)

Back inside after an attempt at astronomy. Cold, very cold, breezy. Bad target selection where all the double star targets I tried were too tight and/or too faint for the little Meade ETX 90.

After a warm-up break, I found everything frosted. Pisces, Eridanus, and Cetus targets were now too low.

Unfortunately, Sirius was not clear of the big tree to the south. So my particular location in the backyard proved unfavourable for my Sirius B split attempt. Tried the new diffraction mask but it was for naught.

As well, the eyepieces immediately fogged when I tried to use them. High humidity now? I considered the dew heating gear or quitting. I quit.

Actually, it was good timing. Clouds moving in. Really cold: -16 with the wind chill.

Motor note was different. And I could see it jumping. Very distracting at medium power, to the point where I turned off the motor. Will have to open it up. Again!

Thursday, January 07, 2021

drove Super Polaris with Stellarium

Wow. It worked. The following documents how to drive a GoToStar motor drive system with Stellarium 0.20.4 via ASCOM.

I was not hopeful at the early stages...

With the intermediate level 2 Stellarium training course for RASC members coming up soon, I wanted to make sure I had a working solution for showing the Stellarium software actually slewing a telescope mount in real time. 


mount setup

With no estate items around or mounts in the repair workshop, the only immediate option was to drive my old mount. In theory, this is possible: it works fine with SkyTools (via ASCOM, using a Vixen driver). But I hadn't done it with Stellarium, ever, I think...

I vaguely recalled getting Stellarium to drive Phil's Losmandy mount, after building a custom cable.

I considered making a simple platform for supporting the Vixen Super Polaris mount. For quick tests in the past, I just held the mount to make sure it didn't tip over. For the course, I'd want to operate it, mostly hands free, and put a camera on it, to show it moving and working. Perhaps a large piece of wood, a square or rectangle, could work, with a hole in the centre, and a bolt into the mount. I've lots of plywood lying around...

But I'd have to counter-sink it... Or layer two sheets...

Couldn't find a large bolt compatible with the SP mount. Metric?

Briefly ruminated on attaching it to the Motomaster work table, like what I did for Wayne's Sky-Watcher equatorial mount, as I reviewed the EQMOD software. Stared at the knob used to hold the Vixen mount to the tripod. Was this long enough to go through the table top? I decide this option was too bulky. And too far from my desk. I needed something in arm's reach, particularly if a slew went bad...

When it slowly dawned on me... Just use the tripod! 

Huh. Set the tripod up by the desk without opening it fully. This would work. Attached the mount. Hey, look at this! It was in the field of view of the TANDBERG camera. Serendipitously, I realised I just solved the problem of "filming" or showing the (portable) mount in action while operating the software. A few checkboxes ticked for the future course prep.

Attached all the GoToStar bits including the amazing hand controller and the AC power.


Stellarium plug-in

Fired up John Gomez, the Windows 10 laptop with the 64-bit version of the OS installed.

Jumped into Stellarium 0.20.4 (64-bit), last used for the introductory training on 28 Dec. Activated the Telescope Control [SIC] plug-in.

Saw there is built-in "direct" driver support for Celestron NexStar telescope mounts, the Losmandy G-11, a few Meade products, a couple of Sky-Watcher mounts, and Wildcard Innovations Argo Navis. Neat. Noted other connection options. I've no idea what RTS2 telescope is. INDI/INDIGO is for the Linux platform, I believe. And by using the "nothing" option, one can employ the simulator mode.

No ASCOM. Hmm. I wondered why...


cabling

I connected the GoToStar "data" cable to the hand controller. This is the computer-control cable terminated in a serial DB9 connector and 4-conducter registered jack.

Moving on, getting more of the puzzle pieces, I grabbed my USB-serial adapter. And I recalled this might not work, the adapter being too old to work with Windows 10. I surfed the internets to see if there was a new driver for the Prolific chipset. And confirmed my adapter, with the HXA circuitry, was too long in the tooth. Physical parts too old so no software workaround. A dead end. Hmm. 

Hold on a sec'. I checked a bin in the workshop and saw a loaner USB-serial dongle. w00t! I recalled using this one during the EQMOD testing, in fact. So, known-good adapter. I connected it to the Dell laptop. Boop-beep. Looked up the assigned port number. OK. Next?


ASCOM software

Checked if I had ASCOM installed on the Win10 machine. Couldn't tell. But I'd need the mount driver anyway.

Downloaded and installed ASCOM Platform 6. It checked out OK.

Downloaded and installed the Vixen SkySensor 2000 PC driver. This is a known-good driver for my hacked IDEA GoToStar motor mount kit.


mount profile (part 1)

Back in Stellarium, in the telescope-mount plug-in, I spotted a new item: ASCOM. Yes! Stellarium had automatically detected the presence of the previously-installed platform. That was easy. 

Still, to be nit-picky: it's too bad an ASCOM entry does not show in Stellarium but perhaps dimmed and with a pop-up note. That would show it's possible but you have do something first...

I attempted to build a profile to the Vixen/GoToStar mount.

And hit a wall...

In the ASCOM "telescope" section, on choosing the Vixen SS2K driver, I received an error message. I interpreted the message to mean that the SS2K driver was not compatible with the 64-bit environment. 

Kicked off some research for find a solution and starting going down a gloomy rabbit hole. Various posts in forums were discouraging. I quickly read the notes on the ASCOM website and found them disheartening.

The SS2K driver 32-bit. Would a solution require the developer of the SS2K driver to make a new version, compiled for 64-bit? I didn't think it likely that could happen.

Windows was 64-bit. There was no way in the-heart-of-a-star I was going to roll that back.

The ASCOM platform was 64-bit, I assumed. I started to pursue a path of trying to get the ASCOM platform to work in a particular way. I could just download the 32-bit version of that. But after a lot of searching I couldn't find anything. Where was the 32-bit version?

Was this a dead end? 

It sure felt like it.


a rethink

So, I actually stopped progress along this path. While not ideal, I wondered I could use the old ASUS netbook. Old version of Windows, 32-bit—so be it. It had ASCOM. And the SS2K driver. Already working fine. A known-good USB-serial adapter too. John Repeat Dance had Stellarium loaded, although I knew it was old. I could update it and then it should work, right?

Launched the planetarium app. Ha! Version 0.12.4. Really old. Had a look around before removing it. A lot has changed. I was confident I wouldn't lose anything critical. I had all the custom landscapes (DDO in the winter, CAO with Dietmar's high-quality images, etc.) archived. Potentially I'd lose some solar system stuff but then... I couldn't think of any specific thing that was relevant.

Downloaded 0.20.4 in 32-bit and started the installer. Boom. It wouldn't run. Oh oh. New Stellarium no longer works on Windows XP (I know, I know). New roadblock.

How far back would I have to go? Searched the Stellarium archives and found that I only had to go to 0.19.0 for XP support. All right, that version should be fairly similar to the 0.20.x. The installation went OK. But on launching the app, I received a strange error message in reference to the dynamic link library msvcrt.dll. Another roadblock, this time, something to do with the .NET framework, it seemed. Ugh. I did not want to have to sort that.

Rebooted. Tried again. Dead end. 

And I had broken Stellarium on the netbook in the process. Crikey!


re-read

Slept on it but was feeling downtrodden about the whole thing. And getting nervous for my course prep.

Dove back into the ASCOM website and re-read the note in the FAQ. The question below was my issue:

The ASCOM Diagnostics program gives me the error "Incompatible Driver xxxxx.  This 32 bit only driver won't work in a 64 bit application even though it is correctly registered as a 32bit COM driver.  Please contact the driver author and request an updated driver.

I read the remarks and somehow something clicked. A light-bulb moment. I think I had not fully understood this particular statement.

If you see the same error when you try to choose the driver in the Application then this is a problem because the application is running as 64 bits and a 32 bit application will not work.

They were talking about planetarium application. Stellarium, not the ASCOM platform. Oh! So if I have the 32-bit Stellarium, it will talk to the 32-bit mount driver... Bingo. There it was. There was the answer.


the app

Hopeful, I uninstalled Stellarium from John Gomez. I had no attachment to the current setup, so nothing stopped me. No significant investment in terms of settings, configuration, customisations. 

Downloaded and installed Stellarium 0.20.4 compiled for 32-bit (x86 for those in the know). Of course, that went swimmingly.


mount profile (redux)

Launched the fresh app and activated the telescope-mount plug-in. Shutdown.

Launched Stellarium again and accessed the telescope-mount plug-in. 

ASCOM entry present, no surprise. Told Stellarium I wanted to use the ASCOM method.

At the ASCOM platform stage, held my breath and selected the Vixen SS2K mount driver. It worked! No error. Just a warning... Don't forget to set the port. Right!

Hit the Properties button. Ah. Familiar Vixen SkySensor 2000 dialogue box. Configured the communications COM port to match the Win 10 assignment. Done! A big milestone.

This signified that 32-bit mount drive was happy receiving commands from a 32-bit planetarium app.

Finished the Stellarium mount profile.


mount config

Now, I needed to configure the Vixen/GoToStar mount hardware, to get it in normal operating mode.

Did the usual stuff: powered up, verified the location, set the date, time, time zone, did a quick (fake) one-star alignment (it suggested Albireo), and I ensured the mount was tracking in sidereal mode.


connecting

I was ready to test intercommunications. Ready to connect the Stellarium software app to the Vixen/GoToStar mount equipment.

Zoomed out in Stellarium to see the whole sky.

Accessed the telescope-mount plug-in. 

Hit the Connect button. Of course, the Status column shows a positive indicator but that may not mean anything. It's a milestone but may be misleading... the incorrect mount driver may not send proper commands for slewing. The connection indication does not verify a full working system.

I was thrilled though to see the reticule (labelled with the mount profile name) suddenly appear in the Stellarium sky display and then move. Woo hoo! This was a major milestone. And then, and then, the reticule settled on beta Cygni! That was huge. The significance of this milestone was that it showed two-way communication. The mount was telling Stellarium where it was! 

I was so happy.


slewing

Immediately I wanted to conduct the next test, the most important one. I tried the slewing keyboard shortcut. Clicked a nearby star in the Stellarium display then pressed the Ctrl key with the appropriate telescope-mount profile number. 

It worked! 

Holy Universe! 

The Vixen Super Polaris mount hacked with the GoToStar motor drive system slewed to the target. Of course the reticule mimicked the movement through the sky.

Amazing.

Tried the slew-to-the-centre-of-the-screen trick with Alt and the profile number. Never used that before. It worked just fine. Neat.

And had a good look at the Move telescope window in Stellarium, also new to me.


finish line

Wow. Relief, joy, satisfaction, elation, pride, calmness... 

I had surmounted this little mountain. Lots of moving parts in this scenario. But I had a solution too. Happy that I would have the ability to show a full run of driving a mount with Stellarium. The key takeaway was that I needed a 32-bit version of Stellarium to properly talk to the 32-bit mount driver. 

screen snap from test video, Stellarium commanding Vixen mount

And along the way, found a way to capture it. In fact, I immediately recorded session in Zoom to see it all work, shared screen from John Gomez with Stellarium, with a head shot including the mount and hand controller working by manual and software control.

Wow.

Wrote up notes in a slide deck... A bit more course prep.

Obviously, this is only one solution. But some of the broad strokes will be the same for all. Hopefully this might help others too, in some of the technical issues that may arise.

Wednesday, January 06, 2021

helped at RAN

Helped at RASC RAN meeting. I worked backstage and was the questioner for our members presentation, relaying questions from the YouTube chat, and throwing in a couple of my own.

Raw video online in our YouTube channel.

§

More than one member asked about the pub after. Huh. That's interesting...

astonished by bad article

This is so bad...

I laughed out loud. Then gritted my teeth. 

Was this written by a robot?!

The "science" article entitled Here’s how to watch the stunning quadruple meteor shower tonight by Maria Gill posted on the Vaughan Today web site is shockingly bad.

Let's start with the title. It refers to the "quadruple meteor shower." Wrong-o. The name of the meteor shower in question is the "Quadrantids." That's a terrible spelling error.

The photo shown (without credit as far as I can tell) is of the night sky from an extremely dark location, with mountains in the distance, and visible aurora. Good luck seeing anything like that in the city of Vaughan. Yes, there's a meteor in the shot. That's good. 

First paragraph: "The quadruple meteor shower is at its zenith, and North American skywatchers have a good chance of seeing the tail end of the show tonight."

The gross spelling mistake repeats, so it's not a glitch in the title, or an issue with an uninformed editor. The author (and editor) are unaware of the proper name, perhaps. Or didn't do a proper spelling check.

Also, I would not use the word "zenith" in this context. That's an astronomical term that may be misconstrued. The author means high point. Normally, astronomers refer to this time as the peak. Zenith is the point in the sky directly overhead.

Second paragraph starts: "This annual meteorite typically peaks between January 3 and January 4 each year." Nope. You can't do that. You can't use the word "meteorite" now. Meteor and meteorite are not interchangeable terms. My trust in the author dropped here! Clearly, they do not have a science background or do not understand the astronomical significance. A meteorite is a meteor that's reached the ground.

Then, "I submitted this year so far Less than ideal views for sky watchers, Given that the moon was 81% full overnight on January 3rd."

Grammar issues aside, the author refers to moonlight. That's good. That's important when trying to view meteor showers. Moonlight interferes with viewing, regardless of location.

Then, the third sentence... "The quaternary meteorites are rather faint, so moonlight can easily wash them off."

What? What?! 

This is written by a robot!

Or a human who's letting their robot spelling checker run amok.

It's NOT the "quaternary" meteor shower.

And we've already discussed it is NOT "meteorites."

Finally, "wash them off." Yes, they are like dirty snowballs... Heh. It is a "shower" after all. But the author means to see "wash them out." Sheesh.

This second paragraph concludes with the author saying the Moon is less bright so there might be a chance of seeing something. She does note however the shower is diminishing. That tricky balance...

It's difficult to read on in this poorly written piece.

Next paragraph starts well, typo aside: "To see the quadruple, find a dark spot with minimal light pollution." Yes, get in your car and travel, during a lockdown period. Sure.

"Beat moonrise or wait until after the moon has set if you can." Does the author understand the dynamics of this? Meteors are often best viewed after midnight. Moonrise on Jan 5 is at 12:30 AM; it's up through sunrise. It's Third Quarter phase, so half-lit, fairly bright. It was worse a day or two before. Does "beat moonrise" mean view before the Moon rises? Not so good.

Has the author even seen a meteor?!

Next: "Meteors appear to emanate from the constellation Boötes." Wow. Look at that. Finally, a good bit of science. Proper word. Reference to the radiant area. And the constellation name with the accent! Astronomers often omit that! And, yes, the radiant is inside Boötes, technically.

The author goes on to explain where to look, using sign posts like the Big Dipper and Arcturus. The radiant is actually a bit west of that. A minor technical issue. Sadly the author does not use easy references like north-east. Also, it seems the author has not realised the radiant is 15° above the horizon at 12:30 AM. And Arcturus but three degrees! Hello.

All that said, experienced observers know to look elsewhere. Not at the radiant...

The final sentence in this paragraph: "You can find out when this constellation ('radiant' meteor shower) will be above the horizon..." Oh boy. This is all wrong. A constellation is not a radiant meteor shower. The radiant of the Quadrantids meteor shower is between Boötes, Draco, and the Big Dipper.

Next paragraph says, "During its climax, which lasts only a few hours, a quadruple shower can produce about 120 meteors an hour. At off-peak times, viewers may still see around 25 meteors per hour." I concur with the 120. But I don't know where the 25 came from. I'll have to check that. But my understanding is that most meteor shower activity off-peak is much lower.

In the second last paragraph, for the first time, the correct term is used.

"Quadrantids are a volley of space dust and rocks from the asteroid 2003 EH1, which is likely an extinct comet that has lost its long icy tail."

Poorly written. The meteoroids (ha) or rocks and dust particles in space we believe come from an asteroid. That asteroid may have been a comet. And we don't know if it had a long tail. Not all comets do.

"Meteorites got their name from the name of a constellation that does not exist now, Quadran Morales..."

Meteors. And it's Quadrans Muralis.

The last sentence in the penultimate paragraph: "The name of the meteor shower associated with Quadrans Muralis has not changed, although Quadrantids are sometimes known as Bootids."

Oh! They got the retired constellation name right this time.

Bootids?! No, that's a completely different meteor shower!

Wow.

The closing paragraph talks about the next shower.. the Lyrids, peaking on April 22. Good. Fair warning there. Except the Moon will be 74% illuminated!

Thanks anyway.

The author segues to the EarthSky web site. Is that where all this bad info came from?

It's too bad the author did not refer to NASA for good science. There's a good article on the Quadrantids.

It's too bad the author did not refer to the International Meteor Organization or the American Meteor Society, what I would consider trust worthy, reliable, accurate sources of information. The AMS notes the "Quadrantids can be one of the strongest displays of the year, yet they are difficult to observe."

It's mind-boggling to me that something like this can be put out there. It's embarrassing for a news outlet to release something so factually wrong. Dozens of errors!

More... selling newspapers.

Again, this kind of thing is infuriating to me. Science communication, increasing awareness of astronomy, getting people outside and looking up is good. It's real good. But hyping, misrepresentation, bending the truth? Don't do that. And don't cry wolf.

Also I'd argue the timing of this is all wonky. We're after the peak of the Quadrantid meteor shower. Attempts to see lots of meteors on Jan 5, the date of the article, is fraught with frustration. Recommendations to view meteors should be released in advance of the event. Doesn't make sense to do it after.

And no mention at all of weather, that you'll likely be clouded out. No mention of the Geminids. No mention of the Perseids. It'd be good to frame things. Mathematically, the Geminids and Quadrantids are the best showers of the year. But people in the northern hemisphere usually miss the show due to grey skies...

I submitted a comment. Awaiting moderation. We'll see...

§

Spotted an article about a "double peak" with the Quadrantids this year but now I can't find it...

§

My comment was deleted! Unapproved.

gaps at the library

I was disappointed to discover that Terry Dickinson's books are not at the public libraries. I tried to find NightWatch. Nothing. Looked under the author name. Nothing. That doesn't seem right...

Tuesday, January 05, 2021

looked up Sirius transits

SkyTools to the rescue once again...

I wanted to know when Sirius was hitting the meridian. When it culminates will be the best time to try to view the double star and it the dim companion. Started in Stellarium and used the sidereal day advance but that was too slow.

Opened ST3P. I used the Ephemeris tab in the app requesting the best time to view the brightest star in the night sky.

Nightly Optimal Viewing Ephemeris for Sirius

Date of Evening Time Dark %
2021 Jan 3 00:14 80
2021 Jan 4 23:02 85
2021 Jan 5 00:00 86
2021 Jan 6 23:57 86
2021 Jan 7 23:53 86
2021 Jan 8 23:49 86
2021 Jan 9 23:45 86
2021 Jan 10 23:41 86
2021 Jan 11 23:37 86
2021 Jan 12 23:33 86
2021 Jan 13 23:29 86
2021 Jan 14 23:25 86
2021 Jan 15 23:21 86
2021 Jan 16 23:18 86
2021 Jan 17 23:13 86
2021 Jan 18 23:11 86
2021 Jan 19 23:03 84
2021 Jan 20 22:58 83
2021 Jan 21 22:55 82
2021 Jan 22 22:52 80
2021 Jan 23 22:48 79
2021 Jan 24 22:44 77
2021 Jan 25 22:40 75
2021 Jan 26 22:37 74
2021 Jan 27 22:34 74
2021 Jan 28 22:31 74
2021 Jan 29 22:29 75
2021 Jan 30 22:29 76
2021 Jan 31 20:52 85
2021 Feb 1 22:06 86
2021 Feb 2 22:10 86
2021 Feb 3 22:07 86

So at midnight right now but creeping to earlier times as the month wears on... 11 PM around the 19th; 10 PM when February starts...

Monday, January 04, 2021

made a diffraction mask

Popped into my churning head today, through the doom and gloom, that it is high time to view Sirius and to try to split out The Pup, the extremely dim companion to the extremely bright parent.

Well that meant I had to find the special mask I had made, some time ago. 

Lost in the entropy of my desk...

After a search of a few other possible spots, I decided to go back to the old notes. Dove into Evernote and located the entry last edited 1 May 2020. I had found an article on apodisation in a telescope.

Provider: SAO/NASA Astrophysics Data System (ADS)
Title: A systematic review of aperture shapes
Authors: Schultz, A. B. & Frazier, T. V.
Journal: Current techniques in double and multiple star research Lowell Observatory Bulletin (ISSN 0024-7057), no. 167, 1983, p. 36-38; Discussion, p. 39.
Courtesy: the Lowell Observatory

From wikipedia:

Apodization is used in telescope optics in order to improve the dynamic range of the image.  For example, stars with low intensity in the close vicinity of very bright stars can be made visible.

Purportedly Herschel and Dawes used apodising diaphragms in the 1840s. 

I had grabbed a snapshot from the paper showing the various mask designs. All featured a cross-member. The first family had a circle aperture with different inner and outer diameters. The second pair had a square aperture. And the last was based on a hexagon. It seemed that the square or diamond was best.

I recalled making a square mask template in Visio so I tracked down the file. Found in my double stars folder, surprise, surprise. Oh. Made on 6 Jan 2019. Makes sense. This is the time (seasonally) to think about challenging unequal double stars...

Fired up the ap. The vector drawings looked good.

mask based on Plate 3.a from A systematic review of aperture shapes

This was the original diagram I made to envision the mask and establish the scale.

Visio diagram for printing and cutting

The second diagram I developed for the printing and cutting. But when I finished printing it, I realised I had overanalysed it. Unlike the Bahtinov style mask, I didn't need to cut dozens of openings. This was much simpler. I could work monolithic... This avoided cutting separate fine strips (the spider), the central square (occulting mask), and all the gluing. That was good. I couldn't find any paper glue...

I grabbed the Stanley box cutter, a backing plate, and Fancii close-up specs and set to work removing the thin L-shape pieces. Done!

Made a cylinder right on the dusty Meade ETX tube. 

Oops, found a decayed elastic band on the 3D printed finder adapter. Installed a fresh band. 

Repair done, I taped the mask in situ to the ring with Scotch Magic tape.

mask and OTA ring

Fits snuggly but can be rotated.

Put my mitts on the Celestron 26mm Plössl ocular.

Did the seasonal tree ball decoration light-bounce trick with the single LED Rayovac torch.

star-like point reflected in Xmas ball without mask

Added the new mask to the OTA. 

false star with diffraction spikes caused by mask

Look at those lovely long thin spikes! They are longer to the eye than in the photo! It works! Or, it should...)

OK. Ready for the next clear night.

Ah ha ha ha ha ha ha ha ha ha ha...

§

Pix with motorola e6.

Sunday, January 03, 2021

proofed next BU article

I agreed with all the highlighted edits already present. I reworded one clunky sentence. The links worked fine. Let Nicole know. I was happy after proofreading my Binary Universe column piece for the next RASC Journal.

helped with rehearsal

Helped with Recreational Astronomy Night dress rehearsal. Looks like I'm on duty as the questioner. First RASC Toronto Centre meeting of 2021 coming up soon, Wed 6 Jan. Good to have Bryon on board! Nice to see Tom O back with an update on his ATM projects.

added occultation dates

Added some double stars occulted by Moon in 2021 to my personal sked. This was based on the double star grazing events in the new RASC Observer's Handbook.

sent out course info

Updated London RASC member Harold on the Stellarium webinars and courses.