[Aavso-photometry] Questions about observation time and air mass

[Michael Koppelman]

On May 22, 2007, at 3:19 PM, Barbara G. Harris wrote:

> 1.        This may be splitting hairs but should I report the start  
> of the
> observation or the mid time of the exposure for the observation time?

Mid. It's a good idea to test your software to make sure you know  
what it is doing.

> 2.       I know AAVSO has an air mass calculator but I use the Sky  
> 6 for
> telescope control and in the object information window they have  
> air mass
> for the object.  The few times I have compared it to the online air  
> mass
> calculator they have been very close (1.21 given by the Sky 6 and  
> on line
> calculator gave 1.2085).  Is the Sky 6 value close enough to report or
> should I stick with the online air mass calculator?

1.21=1.2085 to the reported significant digits. 2 digits after the  
decimal point is probably, in general, plenty for airmass, so you are  
fine either way.

Cheers,
Michael
http://www.lolife.com/astronomy/