My Routine For Setting Up And Imaging For A Night
Astrophotographers around the world will have their own routine for setting their equipment up for the night and the different stages involved in capturing data. This is what I do for a typical nights imaging.
1. First I move my system out of the locked shed, as it is all set up on wheely bars this is relatively easy.
2. Then I position it so the RA axis of the mount is roughly aligned to North, I find using my portable GPS with digital compass helpful here.
3. Next is ensuring the mount is level, the 3 feet on the wheely bars have adjustable levelers and I use these in conjunction with a small spirit level on the base of the mount.
I try and do the above three stages when it is still daylight as it is easier and also it doesn't eat into valuable imaging time.
4. I use a long extension lead from the cellar to the shed where I can connect all the relevant power up for the mount, dew heater, laptop and ccd camera. All the relevant cables are connected up to the mount, laptop and dew heater but I leave the camera at this stage.
5. When it is dark enough I switch the laptop, dew heater and mount on.
6. Start the Sky 6 software and establish a link with the mount, the software tells me to home the mount and with a click of the mouse the mount moves to a fixed position.
7. Next I pick a star using Sky 6 that is relatively close to the home position and click "slew", the mount will then slew to this position, using an illuminated reticule eyepiece I centre the star in the eyepiece using the manual azimuth and altitude adjusters on the mount (it is important not to use the joystick or software to do this at this stage). When the star is centred in the eyepiece I click on "sync", now the mount is roughly aligned to the celestial pole.
8. To get the mount to point accurately and to get the polar alignment more accurate for imaging I do a mapping run of 15 stars using T-point (some people use up to 100+ stars for improved accuracy but I find 15 works ok). To do this I slew to a star using Sky 6 and then use the joystick (not the manual adjusters on the mount) to centre the star in the eyepiece, then click on "map". This is repeated for 15 stars. When this is done T-point will now tell me how far away I am from the celestial pole and it will tell me how much adjustment I have to make using the manual adjusters on the mount. I make the adjustments and then delete the T-point model. To get more accuracy I slew to another star but this time use the joystick to centre it in the eyepiece then "sync" again. Then I do another 15 star mapping run as above. After this second run I find I am within about a 1/10th of an arc minute of the celestial pole. This is accurate enough for long unguided exposures with the Paramount ME. This whole process of getting accurate polar alignment takes about half an hour from the initial "sync" which is a fraction of the time it would take to do an accurate polar alignment using the drift alignment method and I think the T-point method is far more accurate. By this time the pointing accuracy of the Paramount is so good that all objects are dead centre.
9. I now take the eyepiece and star diagonal out and put the camera in place and connect it to the power supply and the laptop, I then start up Maxim DL and establish a link with the software.
10. Next is focusing and this is something that needs a bit of time spent on it, I slew to a star that isn't too bright or dim and set an exposure that will give a good image on the screen. Although I have got an electric focusing unit I find the 2 stage focuser on the TMB so good that I use that. I look at the images of the star and the focus analysis in Maxim DL until I have achieved best focus. Most people would recommend that you monitor focus during the night as temperature changes can affect the focus, this is something I check on each image as it downloads but to be honest I haven't found it necessary to make any adjustments during the night.
11. Now I am ready to image about an hour after originally switching the mount and laptop on. I slew to my first object (it helps if you can plan your imaging session), then I take an exposure just to check if the framing and orientation of the object is to my liking, I make any necessary adjustments and then I am ready to do a run of subframes on that object.
12. I have been concentrating on Ha imaging because of light pollution so I have been using subframes of 10 minutes, as there is some noise I use the simple autodark facility in Maxim DL so when I have sorted out the image directory to download the images to, the length of exposures, number of exposures and binning mode I click on start and the software tells me to cover the camera so I put the lens cover on and click ok, when it has finished the dark frame the software tells me to uncover the camera which I do and wait for a few seconds to let any vibrations settle before clicking ok and then I can leave the software and the mount to do their work.
13. I always monitor the first image or so to check everything is running ok. Here is a tip which I learnt from experience - switch your screen saver and power saving facilities off on the laptop as it may cut in and cause problems, but here is a real useful and essential tip --- If your laptop has WI-FI and you use a wireless modem in the house make sure you switch OFF the WI-FI on your laptop. I forgot to do this the one night and went inside to have a coffee and watch a bit of TV as everything was running smoothly and the weather was good. Anyway when I went back out an hour later the laptop had rebooted following windows deciding to download the latest updates and restart itself, losing my connection to the telescope etc. I am wise to this now.
14. I must admit I like the hands on approach so I tend to spend most of the time outside in the shed monitoring things and I usually find a good crossword helps while waiting for images to download. I always make sure I have plenty of hot drinks during the night and remember to move around often, I also go indoors occasionally for a warm up. Depending on the weather I will stay up all night until it gets too light to image and my longest session has been from 6pm in the evening till 7.30am the following morning.
15. If I have several nights off from work and the weather is good I will leave everything set up outside apart from disconnecting cables and cover the system with the Tele Gizmos cover.
16. When I have unplugged everything if I am not falling asleep on my feet I will start processing the images otherwise I go to bed for a couple of hours.
Some people will have a very different routine but this works for me.