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Eclipses No(s): 104
State: Rising
Accretion disk-dominated U/L/S eclipse profile. Appears to be acceptable quality data even during the Moon up high.
MaxAttachments:
Eclipses No(s): 103
State: Quiescent
U?/N/A.Attachments:
Eclipses No(s): 102
State: FadingAppears to be U/H/PEH again, first seen during the fading stage. Prolonged standstill on the egress, potentially signifying a compact bright spot. Assuming this is correct, post-egress hump (PEH) could be explained with an optically think accretion disk, and not an extended bright spot, although we have seen PEHs appearing during outburst stages as well.
Max
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Eclipses No(s): 101
State: OutburstJust when I thought I’ve seen it all, yet another surprise from CG Dra. The data is noisy, as it’s getting low on the sky, slightly over 30 degrees at midnight, with the Moon visible early in the night and clouds interfering throughout. The profile appears to be U/L/PEH – U-shaped, low orbital hump, post-egress hump (PEH), however, PEH appears to be very wide, lasting about half of cycle. Almost like an anti-phase orbital hump. I don’t remember seeing this profile before. Note, also, a single spike to almost 15.6 magnitude.
Max
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Eclipses No(s): 100 (didn’t show a pic for 99th, partial data)
State: Outburst
U/L/S-type eclipse.Attachments:
These are exactly the cases where the algorithm has failed to fit a Gaussian due to noise or partial data. I also need to resample the data to a finer grid, as described by KvW, to refine the result.
Eclipses No(s): 98
State: Quiescent.
U/N/A-type eclipse.Attachments:
Flat O-C (ignore a few outliers) with P=0.188644 d.
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Eclipses No(s): 97
State: Rising
U/N/A-type eclipse.Attachments:
Eclipses No(s): 96
State: Quiescence
U/H?/PEHAttachments:
OK, I have managed to do Gaussian fits. First, I define a delta phi search region, then identify the faintest magnitude within the search region, smooth out the noise, determine eclipse well and then fit a Gaussian curve to the well. Presenting the first O-C table. Looks like it’s linear. ANOVA period determined incorrectly?
Max
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Thinking how to automate ToM detection for the data collected so far, I have tried fitting a Gaussian function and finding its minimum – see screenshots attached for the last eclipse recorded. Unfortunately, this method is very sensitive to the data boundaries if the data is noisy. If I include more points to the left or right, I get a different curve fit. Even the Kwee-van Woerden method displays the same sensitivity in Peranso. Attached are a few examples. I was thinking to try to find ToM automatically using some predefined phase shift, say, delta phi = 0.2, from calculated minima to set search boundaries, but the choice of delta phi produces different ToM results with both Gaussian fits and the KvW.
Max
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Eclipses No(s): 95
State: QuiescenceTypical U/N/A eclipse for this state.
Max
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Just double-checked my minima calculation: MetroPSF provides the same ephemeris as Peranso, so looks like there is something going on with periods here. I just wonder if there’s an automated way to identify observed minima of all ~ 90 eclipses we have, or is manual the only way? Anyone brave enough to do O-C analysis? 🙂
Max
Eclipses No(s): 94
State: QuiescenceThe eclipse minima definitely has shifted or there is an error in how I am calculating minima. I am puzzled. Can O-C analysis be done in Peranso or some other software?
Max
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Hi All,
Strange things going on… The timing of minima keeps sliding. I’ve plotted the minimum a few days ago and it was right on the observed minimum. Tonight it is about 0.2 phase off. There is very little data, as it was shot through the hole in the clouds, but the eclipse was captured. Either this is a bug in my code or the period keeps changing. But the code here is rather straightforward – I get the epoch time and simply add periods to it to plot lines. How can a period drift by 0.2 phase in such a short period of time?
Code:
if self.plot_epoch > 0 and self.plot_period > 0:
extrema = []
current_extrema = self.plot_epoch
light_curve_start = light_curve[“DATE”].min()
light_curve_end = light_curve[“DATE”].max()
while current_extrema < light_curve_end:
if light_curve_end > current_extrema > light_curve_start:
extrema.append(current_extrema)
print(“Ephemeris extrema:”, current_extrema)
ax0.axvline(current_extrema – 2400000.50, color=”green”, linestyle=’–‘)
current_extrema = current_extrema + self.plot_periodMax
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It did went into bright outburst mode. I’ve been only able to collect 58 measurements this night due to clouds.
Max
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Thanks, Jeremy. Glad to be back.
Eclipses No(s): 93
State: Bright Outburst?It looks like CG Dra is rising into bright outburst mode – this is the brightest it’s been since the last bright outburst. A pattern could be emerging with the last outburst of the cycle being fainter than the previous one before bright outburst – but too early to tell.
Given that this should be an accretion disk (AD) dominated state where no bright spot should be promiment, a bright feature at phases 0.75-0.90, I think, can be interpreted as the re-emergence of the AD from the preceding fade that peaked at phase 0.75 – perhaps, due to the obscuration of a bright inner AD region by the stream overflow. The geometry should be compatible. Within this interpretation, this eclipse is V/L/S-type – V-shaped, no orbital hump, symmetric.
Max
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