Astroblog: But no comet in my scope

Monday, July 04, 2005

But no comet in my scope

Buoyed by the reports of 9P/Temple 1 brightening by 2-3 magnitudes, which suggested it should be magnitude 9-8, I took myself and my telescope outside. Following my Skymap map, I star hopped from Spica to 76 Virginis (easy peasy). Then I started searching in between 76 and 82 Virginis for comet Temple.

Nothing.

A bit of confusion while I reconciled the orientation of the star map with the view through my eye piece, then I star hopped from 76 Virginis to TYC 5545-1356-1, thence to TYC 5546-835-1 and up to TYC 5546-782-1, which should have been within 4' of the comet. I could see stars to 11.7 magnitude, but not the 12.8 mag galaxy PGC 48179 which should have been in the same field. My eyesight is pretty poor when it comes to
dim extended objects, but I'd say it was nowhere near magnitude 8, probably in the range of 10-11.

Over on the comet observation list, Mike Linholt had reported it as having an m1 (that is coma magnitude) of 10.7, so no wonder I didn't see it. The comet listers think the increase in magnitude reports are for the much dimmer nucleus, which is being picked up by the big professional scopes. The coma intensity is much less likely to be dramatically affected. (News flash, Kearn Jones, also of Adelaide, reports an m1 of 10.3, I should have got the 5mm Plossl out, so the comet might have brightened by 1 magnitude unit). The evolution of the brightness of Temple 1 should be interesting over the next few hours. But the comet is too low for me, and I'm too tired, I'm off to bed.

If you are still up, why not pop over to look at the Faulkes telescope images of the impact. Then rush on over to the NASA site for a quicktime movie of the impact. (A tip of the hat to PZ Myers of Pharangula for that, I didn't see it on the site before)

# posted by Ian Musgrave @ 11:16 pm

Comments:

It has been my experience that cometary magnitudes appear (to my eyes) to be a couple of magnitudes less than what they say. If that is really true, I don't know.

Brightening by 2 or 3 magnitudes..WOW!

# posted by

Anonymous : 2:23 am

Peoples eyes vary a bit in their response to diffuse objects. I struggle with comets and planetary nebula that are obvious to other people. Also, being red green colour blind, my visual response to faint colours is pertty messed up (faint diffuse objects mostly stimulate the rods, arther than the colour sensing cones, but for some people a faint stimulation of the rods makes a bit of difference.

Anyway, the comet observers list says that the m1 magnitude (representing the coma, what most of us small scope folks see) only rose by about 1 magnitude (from 11.2 to around 10.5-10.2) while the m2 magnitude (the comet nucleus) webt up around 2.

# posted by