Mars Revisited

2003-08-26:

AO-7 Wiggle

TODO

Setting up for CCD imaging

1. Setup the tripod, attach the wedge and roughly level it.
   
2. Table south of telescope
   
3. Attach te telescope. Make sure the locks are disengaged. The OTA is kept in place by a piece of velcro that's wrapped around it.
   
4. Attach the finder, microfocuser, diagonal and 19mm eyepiece.
   
5. Attach all the cables to the camera, telescope and laptop. I always put the bulky camera power supply on the wedge.
   
6. Level the combination more accurately (using the wedge level).
   
7. Attach the dew shield and camera. Dynamically balance the telescope, disengaging the locks whenever necessary.
   
8. If necessary, cover the telescope and let it cool down for one hour.
   
9. Turn on the laptop, camera and telescope, in that order.
   
10. Make sure Autostar is set to Polar mode. I have told Autostar to do a GPS sync on startup.
    
11. Point the telescope to a bright star, align the finder and focus.
    
12. If necessary, remote the dew shield, collimate the telescope using the camera and attach the dew shield.
    
13. Usually, the camera equipment will not fit through the forks, so the Autostar polar alignment functions cannot be used. But, as an Autostar SYNC resets both the RA and DEC values to the ones of the currently selected object, a SYNC is all that needs to be done when the telescope is properly aligned. Not using any Autostar alignment function, move the telescope to a known star and do an Autostar sync.
    
14. Using the camera, do an accurate alignment.
    
15. Do the Autostar sync afterwards.
    
16. When I turn off the equipment, I first turn off the telescope.
    
17. Determine the seeing condition by taking a well focused 0.01s exposure of a bright star and determine its FWHM.
    
18. If possible, I modify the setup such that the FWHM on this short exposure is between 2 and 2.5 pixels. I find a larger (e.g. 3 pixels) FWHM visually much less pleasing, and smaller would result in undersampling. As the typical rms stellar wander is about half of the FWHM, I reduce the system further to a FWHM of at most 2 pixels when I am not using the AO-7.
    

Techniques

1. Do a PEC before each long exposure, overwriting previous one. This will compensate RA drift caused by imperfect polar alignment. Also gives most accurate PEC I believe.
   
2. Disable X/Y corrections of drive while autoguiding. All corrections should be done by AO-7 only. With proper alignment and PEC, this should be all that's necessary.
   

Mars

2003-07-13: 12 second exposure (300x1/25s) using ToUCam Pro webcam at f/20.

Uranus

2003-07-13: 4 second exposure (100x1/25s) using ToUCam Pro webcam at f/20.

Globular Cluster NGC 6229

2003-05-11: 50 minute exposure (5x600s). Camera cooled to -20°C. Image scale 1.03 arc secs/pixel.

Planetary Nebula NGC 6210 (PLN 43+37.1)

This planetary nebula in Hercules is claimed to have a distance of about 6500 light years. Its central star has designation HD 151121, and according to the Tycho catalog, its distance is 136.7 light years, which doesn't add up.

A SIMBAD search reveals the central star is of type O7, the radial velocity is -35.6 Km/s (moving away from our solar system) and the parallax is an unreliable -4.0±11.00 mas (!), which corresponds to 250pc, or 815 light years.

2003-03-06: 1 minute exposure (1x60s). Camera cooled to -20°C.