Simeis 57 (Cyg), the Propeller-Nebula

Simeis 57 (Cyg), the Propeller-Nebula

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Date/Site: 8., 9., 11., 12., 13. and 14. August 2021. Remote observatory on the AAR club's site in Presberg
Exposure/
Filter:
R: 19 x 300 seconds,
G: 17 x 300 seconds,
B: 11 x 300 seconds,
Hα: 61 x 480 seconds (-20°C)
Camera: Moravian G3-16200 with Astronomik Type II-filters
Optics/
Instrument:
250mm f/4,7 Newton with VIP-3010 Paracorr on 10Micron GM1000 HPS
Guiding: ASI120 attached to a 61mm-finder,
focusing: Microtouch and FocusMax,
data acquired remotely using CCD-Commander with MaximDL 6, and Sequence Generator Pro with PHD2,
processing: MaximDL 6 and PixInsight 1.8

Two attempts creating the data for this image were necessary.
Guiding with MaximDL and the new ASI120 was desastrous. CCD-Commander most of the time was not able to start an exposure, guiding did not calm down to acceptable values. The few frames showed elongated stars and FWHM-values were high like never before. I switched to Sequence Generator Pro and PHD2, because PHD2 worked together with the small CMOS-camera flawlessly. Unfortunately I copied the object-coordinates directly from CCDC into SGPro, without realizing that SGPro uses equinox 2000 instead of JNow as CCDC does. So the propeller landed off-center in the field.
But this image marks a mayor change in the way a modern guiding solution is combined with CCDC.
SGPro for me was just an inadequate makeshift; I had to babysit my gear all night long, because I just did not trust the software. It always failed on the meridian flip and good focusing was a matter of luck.
But the situation changed in June 2021 with a posting in the CCDC-forum, where David Cejudo pointed out the package "PHD_Broker". This collection of scripts allows CCDC and CCD Autopilot to communicate with PHD2, to start and stop guiding, to command dithering, to allow for slewing the telescope and to pause guiding while focusing. MaximDL is only used to control the main camera and FocusMax remains the reliable focusing software of choice.
On top of it AAR-member Carl Herzog introduced us to PHD2's multistar-guiding, a mayor improvement of guiding stability and accuracy.

© Friedhelm Hübner, last revision:  09.12.2024