ASI-2600MCP at +19.5C

[CCD-Freak]

Well....I did it again !!....while getting set up I forgot to turn on the ASI-2600MCP cooling.

Here is about 4 hours of 5 minute subs on the Iris NGC7023 at +19.5C.  NO Darks, NO Flats...just the data.

The 2600 is indeed a special camera.  I love this camera since it works even when my brain doesn't. 8^P

Edited June 29, 2022 by CCD-Freak

[Stuart1971]

Thermal noise is not really an issue with theses cameras, cooling is not really needed…..👍🏼

[symmetal]

The dark current does have an effect at long exposures with higher temperatures but it isn't too bad. The ASI dark current graph is not very readable as the y scale is exponential.

 

Plotting it as a linear graph it makes more sense

Here's the above graph expanded to show the lower temperatures better.

At 19.5C the dark current is about 0.03 e-/sec/pix so your 300 second exposures contain 300 x 0.03 = 9 electrons of dark current. The dark current noise is the square root of this which is 3 electrons. With the read noise at 1.4 electrons the total read + dark current noise is 3.3 electrons so the dark current noise dominates.

At 0C the dark current is about 0.0024 e-/sec/pix so your 300 second exposures contain 300 x 0.0024 = 0.72 electrons of dark current. The dark current noise is 0.85 electrons. The total read + dark current noise is 1.63 electrons so the read noise is the main contributor.

At -15C the dark current is about 0.0003 e-/sec/pix so your 300 second exposures contain 300 x 0.0003 = 0.09 electrons of dark current. The dark current noise is 0.3 electrons. The total read + dark current noise is 1.403 electrons so the read noise totally dominates and the dark current noise is insignificant.

At 19.5C your read + dark noise is 2.4 x the read noise.

At 0C your read + dark noise is 1.2 x the read noise.

At -15C your read + dark noise is 1.002 x the read noise.

So your dark noise at 19.5C isn't excessive John and even combined with the read noise is still much lower than a CCD camera read noise, though cooling to at least 0C is better. 😊

But, with the cooling off, the sensor temperature will likely rise significanly above ambient by around 10 to 15 degrees, so if your ambient is 19.5 then the chip may well be over 30C so dark noise is more significant then. At 30C the dark current noise is 6.7 electrons so dark+ read noise is 6.8 electrons which is in CCD read noise territory.

Very nice image by the way. 🙂

Alan

Edited June 29, 2022 by symmetal

[CCD-Freak]

Thanks

Great  analysis.   I agree that thermal noise is not much to worry about.  (^8

I got the +19.5 from the sensor temperature readout of Astro Art 8.  That is also what is shown in the FITS header.