CT for Caltech, A for the first list of Radio sources published by the Observatory and one (1) for being the first object in this new catalog (discovered by D.E. Harris and J.A. Roberts in 1960)

Well, I have this little thing for supernovas remnants … after CTB1, I saw CTA1 on Astrobin and I was amazed … what a beautiful object. As always for very faint object, I had no choice but shooting with the Hyperstar … I had to catch as much light as I can, and fast ! If you are curious, I found the original paper of the discovery here : https://iopscience.iop.org/article/10.1086/127521/pdf

I must say … I’m not really proud of it … not enough data and I struggled with the treatment of the pictures I took … I’m even very frustrated by this ugly white stain (middle left), it is not a star but a nebula (NGC40, nicknamed Bowtie nebula) … I use to substract the stars from the image to treat the object only so I don’t change anything about the stars, but my tool didn’t catch the nebula as a nebula so when I put the stars back, NGC40 appears white while it is definitively not this way normally … I need to work on it when I have some time, a use of a mask on NGC40 should protect it)

Again, my best setup is about this filter HaO3, it catches both Hydrogen and Oxygen with great results. I still don’t understand why the other filter I have O3S2 needs way more shooting time … I need to figure out this, it spins my mind too much … At the end, this object is really about OIII, quite nothing on Ha or S2 so it’s okay.

I only got one night on CTA1 on Octobr, and waited patiently another slot of clear skies. It happened on the 27 of December but weirdly I couldn’t add the data from the two nights …

• Exifs : Celestron C9 with Hyperstar / PegasusAstro Nyx-101 / PlayerOne Poseidon C Pro cooled at -10°C / Askar D1 HaOIII filter / Guiding System Askar 135mm scope with PlayerOne CeresM

55 lights 300 seconds each

20 biases - 20 darks - 50 flats

Stacked with Pixinsight (WBPP)- Post-Treatment with Pixinsight with a minimum of processes but a lot of tries on adding the two nights shootings. Unsuccesful … maybe another set in this new year 2025.