position 1 - Clear
2 - Red
3 - Green
4 - Blue
5 - Clear
6 - Open (no filter)
The color wheel should be connected to the serial port of the observatory laptop. One can switch between filters using the hand-held, LED-display paddle or with the use of MaxIm DL software found on the Window's-based laptop. When the filter wheel is first turned on, it should automatically start in position 1. Deciding which filter to use for different objects takes practice. Generally, I found that the blue filter produces the best results for nebulae. Taking images of the same exposure length using all three of the color RGB filters can produce a color image during processing time.
1. The first step an astronomer needs to do is plan his or her observing. Pick objects to observe that will be above the horizon and that are in a part of the sky the telescope (and CCD) can slew to. Remember to make sure the telescope does not get in the way of the CCD when slewing! Finder charts may be needed (see LINKS TO OTHER SITES for a good website for this). At this time, the Cumberland Observatory does not have Internet capabilities, so all planning involving the Internet needs to be accomplished before arrival.
2. Plan to arrive at the observatory around a half an hour before sunset (of course if the sky is clear or at least semi-clear!) in order to leave adequate time to cool the CCD and obtain flat field images. Flats should be taken just before sunset in a clear, evenly-illuminated part of the sky (away from the setting sun).
3. Open the dome, take off the plastic telescope cover and the lens caps.
4. Make sure the CCD and color wheel are correctly plugged into the power strip as well as the laptop. The color wheel should be connected to the serial port of the laptop, while the CCD should be connected to the parallel port.
5. Turn the telescope and dome power on (two different switches). You should immediately hear the fans of the CCD.
6. Turn the telescope itself on by the switch on the front panel. Turn on the laptop.
7. Correct the local time on the telescope hand-held paddle. Use your watch to get the correct local hour, but use the digital radio clock in the dome to enter the correct local minute and second. Be as precise as possible when entering this time. The "Hours from GMT" should always be 5, regardless of Daylight Saving's Time.
8. The laptop should now be ready for use. It uses Windows as an operating system. Click cancel during boot up when asked for username and password. When the desktop appears, look for the MaxIm DL shortcut and open up the program.
9. The first thing you need to do is make sure MaxIm DL and the CCD are connected and start cooling the CCD. Do this by hitting the "Toggle CCD Control" button (the eighth button from the left in the top row) or by going to View-CCD Control Window. A box entitled "MaxIm CCD" should come up. At this point, you should just be able to clear on "Connect." If you receive an error, make sure that "Apogee" is set up as the Main CCD Camera, "Same as main camera" is set up as the Autoguider, and "TrueTech" is set up as the Filter Wheel. You may need to reboot the laptop. Even if everything is set up correctly, for some reason, you may have to reboot the laptop once or twice before MaxIm DL is properly connected to the CCD. Once "Connect" works, click on "Cooler On." The CCD will then immediately start to cool itself. Once it reaches -35 degress C below ambient, it will automatically regulate itself at that temperature. At this point, do not close MaxIm DL or turn off the laptop until properly warming up the CCD.
10. While the CCD is cooling, slew the telescope to an evenly illuminated part of the sky (away from clouds and the setting sun) in order to take flat images. Click on the "Expose" tab and then select "Flat" as the type of image. Change the exposure time to 0 minutes, 10 seconds, 0 delay. The color wheel should be in position 1 right now. Make sure it is. Make sure the flip mirror is turned for the CCD. Click on "Expose" and wait. A flat field image should appear. Save this image by clicking on File-Save. Make note of where you save it and what you call it. Repeat this procedure for all the filters you plan to use this night. Switch filters either with the filter hand-held paddle or by changing it in the MaxIm CCD window. For best results, take multiple (like 5) flat field images and then later average them together. Averaging can be done by going to Process-Combine. Make sure all flat field images to be averaged are open when completing this. Make sure to only average flats of the same filter. Each filter may have different dust particles on it, such each flat may be slightly different. Save all the flat images in one folder and save for later when you process your light images.
11. After taking flats, some of the brighter stars should be visible now. Find one of these stars (I like Arcturus during the summer) and enter it's star number (Arturus is 147) in the telescope paddle. Hit the "GO TO" button and the telescope should slew close to that star. Turn the flip mirror so you can find the star in the telescope field of view. Once the star is visually centered, make sure to push the "ENTER" button on the telescope paddle to let it know that it is pointing directly at that star. Now turn the flip mirror back to the CCD. Take a short (3 seconds or less) light image of the star. Do this by being in the "MaxIm CCD" window, "Expose" tab, use "Light" as the type. Set the desired exposure length and filter (it makes no difference which one you use that this point) and hit "Expose" to take an image and wait. An image of the star should now appear. There's no need to save this image. At this point repeat this procedure until the image of the star is centered and in focus. Realize that if you change the focus of the telescope, the eyepiece is going to have to be moved in or out in order to co-focus the CCD and eyepiece together. There really should be no need to refocus every night of observing. In order to center the star, use the telescope paddle, but use a slow (CNTR or GUIDE) slew speed. Also realize the following key to moving the object around in successive images:
In order to move the object: UP Slew: East
DOWN West
RIGHT North
LEFT South
Once the object is centered in the image, push the "ENTER" button on the telescope paddle again to let it now that it is pointing directly at the star. If the star is no longer centered in the eyepiece, you may adjust the flip mirror by turning the adjustment screw on the back of the flip mirror box.
12. Go to View-Night Vision in order to make the MaxIm DL program red and save your night vision.
13. The telescope and CCD should now be ready to take "real" images. If the CCD still isn't cooled all the way, wait. Over the course of the night, take bias and dark images from the "MaxIm CCD" window, "Expose" tab. I would suggest taking 5 bias (you will need to average them together) images sometime over the course of the night. Since both bias and dark are taken with the shutter closed, the filter used makes no difference. Take one dark image for each exposure-length of your light images. For example, if you take two images of M57 (the Ring Nebula), one with 15 second exposure and one with 20 second exposure, you will need to take one 15 second dark image and one 20 second dark image.
1. Slew to the object for which you want to take an image. If it is a bright object, first find the object in the eye piece (and even the view finder if it is that bright). If it is a dim object (such as an asteroid), find a bright object nearby in the viewfinder. You will then need to use your finder chart to slowly slew to the dim object. Unfortunately, the telescope rarely slews to the exact location in the sky that you want it to, so that is why it is always better to find objects in the viewfinder before finding them with the CCD. The CCD has a field of view of approximately 7 by 7 arcminutes. Most likely, you will need to rotate your finder chart counter-clockwise 90 degrees in order to get the correct orientation for your CCD images.
2. Make sure the flip mirror is turned to the CCD. On the "MaxIM CCD" window and "Expose" tab, make sure that the image type is now set to "Light." Enter the desired exposure time and filter (or use the filter paddle to select your filter). Make sure to not over expose images. A minute exposure of something like the moon can actually permanently hurt the CCD.
3. Make sure to save each image as you take it. Make note of the name and location of where you save it. You might as well save each image with a name that will later tell you the exposure. For example, you may want to call your first 15-second exposure of M57 using the blue filter "M57B15-1" Or your third 2-minute exposure of asteroid Hebe using the red filter "HebeR2m-3."
4. You can use the "Delay" option and also the "Settings," "Sequence," "Inspect," "Guide" tabs if needed, but usually you will not need to. The "Focus" tab can be used during focusing procedures to take images with smaller fields of view (and thus speed up the process). Slewing to and taking CCD images of a double star is a great way to make sure the CCD is properly focused. Once you get it in focus, you should not need to mess with the telescope focus knob or with any setting in MaxIm DL.
5. Try taking images of the same object and with the same exposure time but with each of the RGB filters. You can later combine the three images into one color image.
6. Remember the following in order to move an object slightly in the CCD field of view.
In order to move the object: UP Slew: East
DOWN West
RIGHT North
LEFT South
7. Use the "Screen Stretch" window in order to change the "minimum percentile" and "maximum percentile" of the intensity of the image. You may have to change this in order for your image to show up correctly.
8. After all images are taken for the night, make sure to go to the "Setup" tab and press either "Warm Up" or "Cooler Off" in order to warm up the CCD to ambient temperature. Only after it is at ambient, should you press "Disconnect." Once you have pressed "Disconnect," you can shut down MaxIm DL and the laptop. The laptop can be taken away from the observatory to process the images, but make sure you always correctly connect and disconnect both the parallel port (for the CCD) and serial port (for the color wheel) connections.
Note: Other programs such as IRAF can be used instead. IRAF is currently installed on the Purdue HEAP UNIX machines. See other sources for procedures on using IRAF or other programs. MaxIm DL is a good program to use (in my opinion). 1. After opening up MaxIm DL and the image to be processed, click on Process-Calibration Wizard. Follow the self-explanatory instructions. Select "Regulated temperature" as the Type of camera and "Apogee" as the Camera model. Make sure to use the dark image with the same exposure length as the light image (or follow the instructions if the exposure times are different). Make sure to use the flat-field image (or the average of them if you took more then one) of the filter with which the light image was taken. The new image produced after performing the Calibration Wizard should have "cleaned up" the light image. If the image looks worse, you will have to modify this step. Make sure to save this image under a new name. It's always good to save your raw images. 2. You may add pseudo (fake) color to your image by going to Color-Pseudo Color. Experiment for best results. Adding pseudo color may enhance your image and bring out important features. 3. If you have three images of the same object using the three RGB filters, click on Color-Comine Color in order to combine them. Realize you will need to experiment with "Align" in order to make sure all three images are properly aligned. Once the RGB image is produced, you can also go to Color-Realign Planes (this seems to work better). Other options under the Color tab can be used. Experiment. 4. MaxIm DL has many other interested features and is a powerful tool.
1. Take the laptop back to the Purdue HEAP lab (Physics, room 391) and hook it up to the server. Turn it on. 2. Click on the desktop shortcut "WinSCP2.exe." This program can be used to SCP (secure copy protocal, a secure way of FTPing). 3. Use "bohr.physics.purdue.edu" as the host and 22 as the port. Enter your username and password. 4. SCP the desired images onto the server. I usually just save them into my home directory and then use UNIX to move them around later.
1. Use MaxIm DL or a similar program to save your images as a .gif file (.jpg or similar file formats may also be used.) Generally, the images taken with this CCD and created by MaxIm DL are rather big for web images. I saved all of the ones I have posted at 50% size. 2. SCP these .gif images onto the HEAP server. You then need to move or copy them into the following directory: /project/astro/www/latest. 3. Edit (using xemacs or a similar program) the file latest.html so that correct links are added to your pictures. Be sure to change the date on the webpage.
1. I hope these instructions are useful for future users of the Apogee CCD and MaxIm DL software. If you have any questions on the procedure, please see the instruction manual (inside the lap top carrying case). You can also e-mail me at randallecarlson@hotmail.com. I am graduating and departing Purdue around August 3, 2002. 2. This CCD is capable of taking images of brighter asteroids (or other minor planet objects). I tried several nights to locate various asteriods in order to practice and try the MaxIm DL photometry procedure. Asteroids make great and exciting objects to do differential photometry. Because the telescope doesn't always slew to exactly where it should, asteroid photometry is difficult, but with a little patience and luck, you should be able to locate an asteroid with the CCD. After getting an ephemeris from the Minor Planet Center (I added the site as a link), I was able to briefly locate asteroid Hebe on July 25, 2002 (my last night of being able to observe.) Unfortunately, right when I figured out my finder charter and realized which point of light was the asteroid, the pesky Indiana clouds rolled in. 3. This summer was very rewarding and I feel like I learned a lot, but I definitely learned that science (especially astronomy in a humid state like Indiana) sometimes takes a lot of patience and creativity!