Sirius and the Pup

I took the opportunity on March 1st to try and capture an image of Sirius and the Pup, the companion white dwarf to the brightest star in the sky (besides the Sun). I chose to use the Meade 12” LX-90 and the ZWO ASI290MC camera to tackle this image. Information from Stella Doppie ( was showing the Pup at a distance of 11.193 arc-seconds from Sirius, the next few years are prime for imaging the Pup as it is approaching its maximum distance from Sirius.

The snapshot shown was taken from inside SharpCap (v3.2) using a GAIN of 109 and exposure setting of 0.986 seconds. To help confirm this was the companion to Sirius, the camera was rotate to make sure the Pup rotate with the camera.

Camera Settings: [ZWO ASI290MC], Pan=0, Tilt=0, Output Format=AVI files (*.avi), Binning=1, Capture Area=1936x1096, Colour Space=RGB24, Temperature=7.5, High Speed Mode=Off, Turbo USB=100(Auto), Flip=Vert, Frame Rate Limit=Maximum, Gain=109, Exposure=0.98651, Timestamp Frames=Off, White Bal (B)=99(Auto), White Bal (R)=99(Auto), Brightness=70, Auto Exp Max Gain=300, Auto Exp Max Exp M S=30000, Auto Exp Target Brightness=71, Mono Bin=Off Banding Threshold=35, Banding Suppression=0, Apply Flat=None, Subtract Dark=None, #Black Point, Display Black Point=0.015625, #MidTone Point, Display MidTone Point=0.0860025213385175, #White Point, Display White Point=0.881863317757009, TimeStamp=2020-03-02T00:41:25.8219124Z SharpCapVersion=3.2.6137.0

Using the CCD Calculator online at Astronomy Tools ( ), the resolution of the photograph was calculated to be 0.2"/pixel (using a 2.9 um CCD pixel size and a 3,048mm focal length). Measuring the pixel distance from the center of Sirius A to what I believe is Sirius B shows a calculated distance of 12.6 arc seconds, it sure falls in line with the predicted 11.193 separation provided by Stella Doppie.

You can use any paint program to measure the pixel distance between the stars. In this case, I measured an estimated distance of 63 pixels from the center of Sirius to the center of Sirius B. I use Corel Paintshop Pro for this.


The video above is a collection of 50 individual images taken inside SharpCap Pro and then edited and saved in MP4 format. You can clearly see Sirius B on the right side of Sirius.

Tech Specs for all images produced: Meade 12” LX-90, ZWO ASI290MC camera. Captured using SharpCap v3.2. Image date: March 1, 2020. Location: The Dark Side Observatory, Weatherly, PA, USA.