Target fun facts
Sadr or Gamma Cygni (γ Cyg) is a yellow-white supergiant star located in the constellation Cygnus. With an apparent magnitude of 2.23, it is the constellation’s second brightest star, after Deneb. Sadr lies at an approximate distance of 1,800 light years from Earth. It is the star that marks the intersection of the Northern Cross, a bright asterism that dominates the summer sky in the northern hemisphere. Sadr lies in a rich field of the Milky Way and is surrounded by the diffuse emission nebula IC 1318, also known as the Gamma Cygni Nebula or Sadr Region.
Sadr is a supergiant star of the spectral type F8 Iab, appearing yellow-white in color. It has a mass 12.11 times that of the Sun and has expanded to a size of about 150 solar radii. With a surface temperature of 5,790K, the star has a bolometric luminosity 33,023 times that of the Sun. Its estimated age is 12 million years. Even though it is relatively young, it has already evolved away from the main sequence and its mass seals its supernova fate down the line.
Other Catalog Designations: γ Cyg, 37 Cyg, HIP 100453, SAO 49528, HD 194093, HR 7796
Subtype: Star
Distance from Earth: 1832 light years
Magnitude: 2.20
Constellation: Cygnus
{Target information derived from: https://www.star-facts.com/sadr/ and Stellarium }
Capture Notes
I use Sadr as a focus star when imaging objects in Cygnus (or in that region – as it’s rising early so it’s in a good high-sky position when I’m starting imaging during the late summer.
I purchased tri-Bahtinov masks from Joel Short at Buckeye Stargazer Astronomy (https://buckeyestargazer.net/) from Big Bertha and Big Zeus. Once I started experimenting with the EAF, I haven’t really been using the Bahtinov masks. But I decided to let the focusing sequence go to fruition (5x5second images) to capture Sadr with the tri-Bahtinov lens.
I processed this to send to my friend and work colleague, Ken Senechal, who has been using my image of Sadr taken with a Bahtinov mask from 2022 (ironically, 30 Aug 2022) during briefings when he’s making a point about finding our North Star. This still isn’t Polaris (like I keep telling Ken the one he’s using is not) – but pretty cool with the tri-Bahtinov rainbow spikes
Equipment
Equipment: All equipment controlled by HP Probook running Sequence Generator Pro v4.4.0.1339.
Imaging (ASI2400-BZ-LPro): ZWO ASI2400MC imaging camera on (Big Zeus) Orion 10″ f/8 Ritchey-Chretien Astrograph Telescope, TS 2.5” Rack and Pinion Focuser, Teleskop Service Flattener 1.0x for RC Telescopes (TS-RCFLAT2), Optolong L-Pro LP filter (LPro)
Autofocuser: ZWO EAF Electronic Automatic Focuser – Standard (New 5V Version) (EAF-5V-STD)
Mount: Rainbow Astro RST-300 (controlled by iHubo ASCOM driver)
Polar alignment: QHYCCD camera (controlled by Polemaster for polar alignment)
Sequence plan: This is one 5-second image, processed in LR.
Capture: 31 August 2024
Shooting location: HCH, Colorado Springs, Colorado
Processing: Single 5-second image processed in LR