2021-08-02, 08:20 AM
On 19th July I started collecting images at 7:50pm local time AEST (0950 UT) and completed the run at 8:30pm (1030 UT) and I was recording 30 sec exposures through LRGB Filters.
On 24th July I started collecting images at 7:00pm local time AEST (0900 UT) and completed the run at 10:00pm (1200 UT) and I was recording through LRGB Filters.
Although I purposely selected Quaoar for both sessions, I actually wasn’t confidently expecting to be able to record it, but as I was testing some new equipment, I figured why not pick an interesting target.
As with Nereid (moon of Neptune) I have found these mag 18-19 objects very tricky to capture due to their movement against the BG stars. With the fixed stars the photons all arrive at the same location but with these moving objects, their light is spread out over an extended trail and so is much less distinct and does not reinforce across all frames like the fixed stars.
For faster moving NEO’s I can generally record a trail down to around mag 16.5 but any fainter, or faster moving, they don’t leave enough photons on my sensor to record their passage, even though I can obtain fixed stars down to mag 20 from my Bortle 6 skies in Brisbane.
I use PixInsight for the calibration and processing of the sub-frames and with these faint moving objects, the signal is usually just a few counts above background. Some of the processing tools artificially “lift” the edges of the data to increase micro contrast and this can also produce an artificially textured BG where random “noise” might well look like an object.
So, these faint objects are a real test and when I can find a sprinkling of photos above the BG levels and confirm its position with say SkyTools, then I consider it to be a good candidate, but there always remains some doubt due to the very low levels of signal above the BG.
In a clear patch of sky, I am generally more confident of an object but when it is closer to other stars, then I am less confident, as I often see spurious signals around these stars due to the effects of unstable atmospherics and imperfect auto guiding.
But it remains a fun activity and becomes especially rewarding when apps like SkyTools make it relatively easy to find, track and hopefully confirm these objects.
We are going through another CV-19 lockdown in Brisbane right now, so it is therapeutic to have a hobby like astronomy where you can gather data by night and process by day – no time to get bored.
Cheers
Dennis
On 24th July I started collecting images at 7:00pm local time AEST (0900 UT) and completed the run at 10:00pm (1200 UT) and I was recording through LRGB Filters.
Although I purposely selected Quaoar for both sessions, I actually wasn’t confidently expecting to be able to record it, but as I was testing some new equipment, I figured why not pick an interesting target.
As with Nereid (moon of Neptune) I have found these mag 18-19 objects very tricky to capture due to their movement against the BG stars. With the fixed stars the photons all arrive at the same location but with these moving objects, their light is spread out over an extended trail and so is much less distinct and does not reinforce across all frames like the fixed stars.
For faster moving NEO’s I can generally record a trail down to around mag 16.5 but any fainter, or faster moving, they don’t leave enough photons on my sensor to record their passage, even though I can obtain fixed stars down to mag 20 from my Bortle 6 skies in Brisbane.
I use PixInsight for the calibration and processing of the sub-frames and with these faint moving objects, the signal is usually just a few counts above background. Some of the processing tools artificially “lift” the edges of the data to increase micro contrast and this can also produce an artificially textured BG where random “noise” might well look like an object.
So, these faint objects are a real test and when I can find a sprinkling of photos above the BG levels and confirm its position with say SkyTools, then I consider it to be a good candidate, but there always remains some doubt due to the very low levels of signal above the BG.
In a clear patch of sky, I am generally more confident of an object but when it is closer to other stars, then I am less confident, as I often see spurious signals around these stars due to the effects of unstable atmospherics and imperfect auto guiding.
But it remains a fun activity and becomes especially rewarding when apps like SkyTools make it relatively easy to find, track and hopefully confirm these objects.
We are going through another CV-19 lockdown in Brisbane right now, so it is therapeutic to have a hobby like astronomy where you can gather data by night and process by day – no time to get bored.
Cheers
Dennis