| date | time | locale | seen | mag | sep. | alt. |
| Aug 12, 00 | 0600 | rural | no | -1.3 | 10 | 5 |
| May 14, 02 | sunset | urban | ? | 1.7 | 16 | 11 |
| Jun 25, 05 | sunset | rural | no | 0.0 | 22 | 14 |
| Nov 19, 05 | sunset | rural | no | 1.6 | 11 | 4 |
| Jun 24, 06 | sunset | rural | no | 1.0 | 24 | 15 |
| Aug 05, 06 | 0415 | rural | no | 0.5 | 19 | 16 |
| Feb 06, 07 | 1800 | urban | yes | -0.4 | 18 | 11 |
| Feb 10, 07 | 1811 | urban | yes | 0.1 | 18 | 10 |
| Feb 12, 07 | 1800 | urban | yes | 0.5 | 17 | 12 |
| May 18, 07 | 2121 | urban | no | -0.5 | 18 | 8 |
| May 23, 07 | 2000 | urban | no | -0.1 | 21 | 25 |
| May 27, 07 | 2132 | urban | no | 0.3 | 23 | 10 |
| May 28, 07 | 2121 | urban | yes | 0.4 | 23 | 13 |
| Jun 09, 07 | 2135 | rural | no | 1.3 | 21 | 11 |
| May 17, 08 | 2124 | urban | yes | 1.0 | 21 | 10 |
| May 24, 08 | 2045 | urban | no | 1.7 | 17 | 13 |
| Sep 02, 08 | n/a | urban | yes | 0.2 | 25 | 8 |
| Dec 31, 08 | 1645 | urban | no | -0.5 | 19 | 13 |
| Jan 05, 09 | 1710 | urban | yes | -0.2 | 19 | 11 |
| Apr 25, 09 | n/a | rural | yes | 0.4 | 21 | 10 |
| Jun 22, 09 | 0430 | rural | no | 0.0 | 21 | 0 |
| Oct 11, 09 | 0636 | rural | yes | -0.7 | 16 | 6 |
| Aug 08, 10 | 2045 | rural | no | 0.7 | 27 | 7 |
| Aug 11, 10 | 2015 | rural | no | 0.8 | 27 | 10 |
| Jan 10, 11 | 0800 | urban | no | -0.1 | 23 | 11 |
| Mar 16, 11 | 1946 | urban | yes | -0.9 | 17 | 10 |
| Jul 09, 11 | 2145 | rural | yes | 0.3 | 25 | 6 |
| Jul 01, 12 | 2116 | rural | yes | 0.7 | 26 | 10 |
| Feb 09, 13 | n/a | urban | yes | -0.8 | 16 | 14 |
Assuming naked eye or binoculars.
If I remember correctly, my first viewing of Mercury was in the mid-90s, through the telescope.
So, the statistics now. This shows I've seen Mercury as faint as magnitude 1.0, as low as 6 degrees above the horizon, and as close to the Sun as 16 degrees--but not at the same time! When it was mag 1.0, it was 10 up and 21 away. When it was 6 up, and close at 16, it was bright at mag -0.7. I've considered that as I get older, I get better at observing. So I may have simply missed it on other occasions. For example, on my first attempt, it was much brighter. But, at the same time, low and close; arguable.
I don't think these magnitude values take in account extinction...
Now, the point of this exercise to get a sense of what we might expect to see with comet C/2011 L4 Pan-STARRS in early to mid-March. I'd like to know how close an object can be to the Sun to be visible.
Mercury's a point-source, essentially. To the naked eye, star-like. A comet however should have some dimension. This is analogous to stars versus nebulae. Galaxies and diffuse nebulae and the like are "large" objects. And the magnitude value for them is for the "entire" object. If it is a very large object like the Andromeda Galaxy... The magnitude or brightness, another way to think about it, is "spread out."
Some facts on the comet.
On Mar 5, at perihelion, it will appear approximately 19 degrees from the Sun. At a predicted magnitude of 0.8. And, it will be left of the Sun. I.e. when the Sun sets, so too will the comet. So, no good for viewing then. Now, on the 16th, the comet will be above the Sun. And slightly further away, at 21 degrees. But, then, mag 1.1 is expected. Another important fact: comet C/2011 L4 Pan-STARRS originates from the Oort cloud and this will be its first trip so close to the Sun.
This magnitude numbers are from Stellarium. As of Feb 12. And the software pulled these numbers from MPC.
I dunno about you but I don't like where this is going... It is very close to the magnitude numbers for Mercury (at the time of writing). Similar angular separations and altitudes or elevations in the sky. But one's a point source and the other is not. I believe we'll be lucky to see the comet naked eye. And if the comet dims between now and then, I think we might need the telescope...
No comments:
Post a Comment