[Outbackmanyep]

Originally Posted by astroron

Thanks for your post of the Comets I don't have Howell in my data base, but will rectify that soon
What scope and eyepieces used and magnification?
Cheers

Hi Ron!
I'll tell you how to decipher the below details of the scope etc so you can work out other observers details from comets-ml yahoo group if you wish to check up on other comets! Its quite easy!
For example:

88P/ Howell
2009 August 23.37 UT; m1= 9.2; Dia= 8’; DC= 4; 25cm L, f:5 (x39)


The time is given in decimal days and m1= estimated magnitude.
25cm L = 25cm Newtonian (L being the standard letter denoting a Newtonian. B= Binoculars, T= Schmidt-Cassegrain, E= Naked eye, R= Refractor, A= Camera lens)
It gives the F ratio - f:5
and magnification of (x39)
For me to get a magnification of x39 with an f/5 10" newtonian/dob i use my 32mm Plossl.
It's always a good measure to use the LOWEST power possible for comets as image brightness is the key to help detect the extremities of the outer coma for diameter measurements, ie: Dia= 8', if you went to a higher power the image brightness dims and you lose the faint outer edges which lessens the accuracy of your measurement.

The scope is an extension of your eye, and all measurements would ideally be taken using your naked eye but in most cases this is not possible, so using the smallest instrument possible you can make more accurate magnitude estimates. If you notice on my observation of W3 Christensen i also tried it with 7x50 Binoculars as it was bright enough to be observed with binoculars.

I hope this helps! any more questions by all means ask away!