Limiting Magnitude rate of change when zooming

barringtonri Apr 3, 2013

The following message posted as GUIDE QUESTION actually deserves a thread of its own:


Normally, when I view the screen for my ccd size showing the ccd frame,
I want to see 20th magnitude. As I zoom out there are fewer stars
showing but presently there are still too many stars showing in the
wider views. How do I change the rate at which the stars disappear as I
zoom out without changing the zoomed-in values of 20th magnitude? I use
the mouse wheel to zoom.


There were several responses to Tom's question but they too got sidetracked onto the availability of 20th magnitude data. I think that what he was looking for was similar to a situation I encounter. When planning my asteroid viewing for the night I work at full horizon view with star limiting magnitude set unobtrusively to something like 0, 1 or 2 magnitude.

Locating a potential asteroid target I then zoom to level 8 to investigate the star field and the availability of a guide star. At this point I manually adjust the star limiting magnitude to 18 so as to planning framing for my CCD imaging.

Some time back Bill set the star display so that when it is selected the cursor is always sitting on the limiting magnitude selection box, and this made changing desired magnitudes back and forth much easier. But when going back to Z (full horizon view) I frequently forget to reset star limiting magnitude before punching Z. Having set 18th magnitude at zoom level 8, Guide automatically resets limiting magnitude to level 8.9 when I hit Z and as a consequence the screen starts filling with zillions of stars - a sequence that I interrupt with Escape.

Anyway, I THINK that Tom's looking for what I'd like: the ability to adjust the automatic change in limiting magnitude. In my case I'd like to run 18th magnitude at zoom level 8 and perhaps 2nd magnitude (rather than 8.9 mag) at zoom level Z. A manual star limiting magnitude override would still be needed of course.

Can this be done with the existing software setup?

Pete Peterson I15