Astrophotography Targets

In addition to a month-by-month target list, I have included additional information on determining how to configure the SCT for imaging.
 - Imaging List by Month - List of potential imaging targets month-by-month
 - Back Focus Calculations - How far to place your camera for imaging.
 - Image Scale - Getting the best resolution from your system.
 - Dither and Drizzle - Extrapolating higher resolution images from your captured images.

References:
  - Calculators for Astrophotography
  - James Yoder: Filter Comparison for Imaging Broadband Spectrum Object in Light Pollution Area (PDF)

Imaging List by Month

Things to note on documents
 - Grayed targets have already been imaged.
 - Times associated with Transit, and Imaging Window:
 - All times are approximate generally within 15minutes of the estimated event.
 - All calculations are based on Chandler as the location.  If you live in the Phoenix Metro area this should be fine.
 - The date used for the calculations are on the night of the new moon for the month.  These numbers are a pretty good approximation for the week before and after the new moon.

Imaging Window Times are determine with the following assumptions
 - Imaging window cannot start until astronomical twilight and must stop at astronomical dawn.
 - Ideal alt of 45degrees above the Eastern Horizon to the Meridian (Since I live in the East valley, and west has light pollution).
 - Targets low on the Southern Horizon may have an imaging window that starts with them lower then the ideal 45 degrees.  Generally I'll take the transit, and subtract 2hrs as the starting window.

Much of the data used to create this document comes from the following sources
 - www.telescopius.com
 - The Astrophotography Sky Atlas by Charles Bracken
 - LiveSky

Month	New Moon	White	Dark
January	01-29-2025	View	View
2024-02: February	02-09-2024	View	View
2024-03: March	03-10-2024	View	View
2024-04: April	04-08-2024	View	View
2024-05: May	05-08-2024	View	View
2024-06: June	06-06-2024	View	View
2024-07: July	07-05-2024	View	View
2024-08: August	08-04-2024	View	View
2024-09: September	09-03-2024	View	View
2024-10: October	10-02-2024	View	View
2024-11: November	11-01-2024	View	View
December	12-30-2024	View	View

Back Focus Calculations

Backfocus is the distance from the Optical Tube Assembly to the imaging camera.
References
  - What are the optimum back focus distances for Celestron SCTs?
  - How to set the correct back focus for your telescope (Guide)
  - Celestron EdgeHD back focus tolerance
  - Back-Focus 101: DSO CCD/CMOS Cameras & the Celestron f/6.3 Reducer/Corrector (YouTube)
  - Back-Focus 101: Celestron EdgeHD: C9.25, C11 and C14 Advanced Back-Focus with the Celestron OAG (YouTube)

Configuration	Back Focus Target (NBF)	Component And Distance	Component And Distance	Component Distance	Camera	Total
C-11HD Primary Focus	146mm +/- 20mm	ESATTO Focuser 67mm	ARCO Rotator 20mm	Filter Tray 34mm	ASI6200 Camera 12.5mm	Measured 150mm
C-11HD Focal Reducer	146mm +/- 20mm	ESATTO Focuser 67mm	ARCO Rotator 20mm	Filter Tray 34mm	ASI6200 Camera 12.5mm
C-11HD HyperStar	55mm			Filter Tray 34mm	ASI6200 Camera 12.5mm
C6 Primary Focus	127mm
C6 Focal Reducer	90.3mm +/- 2mm				ASI294 Camera 12.5mm
C6 HyperStar

Image Scale Calculations

Image scale calculations require you know the Focal Length of your optical train.  This can be rather difficult with the various possible hardware configurations.  It may be easier and more accurate to obtain the Image scale by taking a photo with the configuration and obtain the Image Scale from Astronetry.net, and back-calculate the Focal Length.  This is how the values below were calculated.

Obtaining the proper image scale for your hardware is important to ensure you can get the clearest images possible for you setup.  Optimum Image scale is dependent upon seeing conditions, so it can vary night to night.  Still it's a good idea of what would be an appropriate rand you may want to shoot for. Generally this will be from 0.6"/pixel to 2.0"/pixel.

References
 - CCD Suitability
 - Astronomy Tools: Field of View Calculator (Imaging Mode)

Configuration	Focal Length	Pixel Size	Measured Image Scale (P”)	Sampling	Measured Image Size (deg)	Comments
C11 \| ASI 6200 \|	2,800 mm	3.76 um	0.280 arcsec/pixel	Over Sampled	0.74^o X 0.49^o	Ideal 0.67″ – 2″/pixel
C11 \| 0.7 Reducer\| ASI 6200 \|	1,960 mm	3.76 um	0.393 “/pixel	Slight Over Sample	1.05^o X 0.7^o
C11 \| HyperStar \| ASI 6200 \|	540 mm	3.76 um	1.4″/pixel	Good	3.82^o X 2.55^o	These values are calculated
C6 \| ASI294\|	1,500 mm	4.63 um	0.64″/pixel	Good	0.73^o X 0.5^o	These values are calculated
C6 \| 0.63 Reducer \| ASI294\|	1,220 mm	4.63 um	0.78″/pixel	Good	0.90^o X 0.61^o	These values are calculated
C6 \| HyperStar \| ASI294 \|	300 mm	4.63 um	3.18″/pixel	Under Sample	3.66^o X 2.5^o	These values are calculated

Dither and Drizzle

Dither is a technique used when capturing images in astrophotography to help create a better signal-to-noise ratio and is the process of slightly shifting the pointing direction of your telescope between exposures.  Generally, I will dither once every two to five images that I take (Three is what I usually use for dithering).

Drizzle After images are captured utilizing Dithering, the Drizzle technique can be applied to the images.  This is a method developed by NASA to reconstruct undersampled images. In the Image above, the Top Left image represents the original object, the Bottom Left is the captured image, and the Bottom Right is the captured image with Drizzle applied to it.  This technique is applied to images when processing (IE in Pixinsight).

References
 - What is Dithering?
 - Astronomy Tools: Field of View Calculator (Imaging Mode)
 - Use Hubble's Drizzle to improve your astrophotos!  Drizzle history and tutorial in Pixinsight. (YouTube)
 - White Paper:  Drizzle: A Method for the Linear Reconstruction of Undersampled Images (PDF)

Configuration	Focal Length	Pixel Size	Measured Image Scale (P”)	Sampling	Measured Image Size (deg)	Comments
C11 \| ASI 6200 \|	2,800 mm	3.76 um	0.280 arcsec/pixel	Over Sampled	0.74^o X 0.49^o	Ideal 0.67″ – 2″/pixel
C11 \| 0.7 Reducer\| ASI 6200 \|	1,960 mm	3.76 um	0.393 “/pixel	Slight Over Sample	1.05^o X 0.7^o
C11 \| HyperStar \| ASI 6200 \|	540 mm	3.76 um	1.4″/pixel	Good	3.82^o X 2.55^o	These values are calculated
C6 \| ASI294\|	1,500 mm	4.63 um	0.64″/pixel	Good	0.73^o X 0.5^o	These values are calculated
C6 \| 0.63 Reducer \| ASI294\|	1,220 mm	4.63 um	0.78″/pixel	Good	0.90^o X 0.61^o	These values are calculated
C6 \| HyperStar \| ASI294 \|	300 mm	4.63 um	3.18″/pixel	Under Sample	3.66^o X 2.5^o	These values are calculated