Observing Night 1 Objects : Name RA (2000) Dec V B-V V-R R-I MK source HD 5015 00 53 04 +61 07 26 5.34 0.54 0.48 0.30 F9V Ducati 2002 HD 30197 4 46 17 +18 44.1 6.01 1.21 0.620 0.533 K4III J66/T86 HD 7615 1 16 28 +23 35.4 6.693 0.047 0.06-0.01 A0 L83b Messier 41 06 46 01.0-20 45 24 4.5 Open Cluster Procedures: DON T FORGET TO KEEP NOTES ON YOUR PROCEDURE AND KEEP AN OBSERVING LOG FOR THE NIGHT!!!!! Set up & Align Telescope: 1. Open Roof, Move 12 outside. 2. Power on telescope 3. One-star Polar alignment: point telescope to DEC=90, HA=0 4. Using eyepiece, center the star that the telescope chooses (or choose another star if the first is not visible) 5. Hook up CCD camera, turn on cooling (Use CCDOps) 6. Rough focus on bright star 7. Double-check that finderscope is well-aligned Standard Star: 1. Pick a standard star and point telescope to it. Make sure you re in the right field! a. You may need to use a nearby bright star to sync the telescope alignment b. The standard stars are all bright enough to see with the finderscope 2. Check your pointing with TA to make sure you re looking at the right object! 3. Choose an appropriate exposure time (do not want > 40,000 counts/pixel, want >10x background if possible) 4. Take at least 10 images in each filter (you will need to check the exposure time for each different filter before you begin) Sky: 1. Take at least 10 30-second images of a mostly empty region of sky at the following locations in each filter: 2. Zenith: alt = 90deg, HA = 0h, RA = LST 3. East: alt = 60deg, az = 90deg; HA ~ -2h 4. West: alt = 60deg, az = 270deg; HA ~ +2
Star Cluster: 1. Warning: won t be high enough to observe until after 9 pm (this shouldn t be a problem though) 2. Point the telescope at Messier 41. Make sure you re looking at the same part of the cluster that is centered in the finding chart. 3. Check your pointing with TA to make sure you re looking at the right object! 4. Choose appropriate exposure time. Some of the stars in M41 are pretty bright, so a short exposure time will work better. 5. Take at least 15 images in each filter (you will need to check the exposure time for each different filter before you begin)--if your exposure times are <10s, take at least 20. Calibration Images: 1. Flats: a. Set up projector light to take flats as directed. b. Find appropriate exposure time for given filter (between 20,000 and 30,000 ADU/pix) c. Take 15 exposures with that exposure/filter combination d. Repeat for all filters 2. Bias: a. Take 10 Dark frames at the shortest possible exposure time for your camera. b. This tells you how many counts in your image are inherent to the readout process. This way you can calculate your dark current. 3. Darks: a. Take 10 Dark frames for every image exposure time. b. For example, if I took 10s exposures for my standard star, 30s exposures for my sky measurements, 30s and 5s exposures of M41 in different filters, and 1s, 3s, and 10s exposures for my different flats, I would take 1s, 3s, 5s, 10s, and 30s darks. I can use the same darks for calibrating both the sky and cluster images, and darks are not filter-dependent (because there is no light). c. Dark current is a function of exposure time, and is related to the thermal noise. The cooler your CCD camera is, the less dark current you will have. Our SBIG cameras are not very well-cooled, but we can account for a lot of the dark current by subtracting it from our science images. Shutdown: 1. Before you turn anything off, check to make sure you have all of your data. 2. Copy data from computer to your own USB drive. Make sure your whole group has access to both the data you took as well as your observing log. 3. Warm up & Shut down CCD. Pack it carefully and put it away. 4. Cover, power off, and put away telescope. 5. Check with TA to make sure you ve got everything put away correctly before you leave.
1/29/2018 create_finding_chart.cgi (3564 3571) Nearby bright star: Navi (visible in SE corner of the finder chart) http://astro.swarthmore.edu/create_finding_chart.cgi?target=hd+5015&ra=&dec=&field_width=60&field_height=60&show_detecto 1/1
create_finding_chart.cgi (JPEG Image, 3564 35... http://astro.swarthmore.edu/create_finding_chart... Nearby bright Star: Aldebaran 1 of 1 1/30/18, 3:11 AM
1/25/2018 create_finding_chart.cgi (3564 3571) Nearby bright star: Sheratan http://astro.swarthmore.edu/create_finding_chart.cgi?target=hd++7615+&ra=&dec=&field_width=60&field_height=60&show_det 1/1
1/25/2018 create_finding_chart.cgi (3564 3571) Nearby bright star: Sirius http://astro.swarthmore.edu/create_finding_chart.cgi?target=messier-41&ra=&dec=&field_width=60&field_height=60&show_detect 1/1