- Date: 17/09/2023
- Time: 21:31 – 22:31 UT
- Seeing: II. Good – Slight
- Transparency: II. Clear with some cloud
- Temp: 14.3C,
- Air Pressure: 1005mb,
- Humidity: 95%,
- Dew Point: 13.3C,
- Wind Speed: 9mph
- SQM:20.01 magn/arcsec^2
Scope: Altair 250mm RC f/5.3 Camera: ZWO ASI 183MM Pro, No Filter. Dark subtracted and Flat fielded.
Is this the shortest – but eventually a successful and satisfying – observing session ever. Open up observatory at 21:31UT. Take and observe a stack of 14x 30 sec subs of NGC7008 ( which is really interesting by the way) log the and read up about the subject, only to have cloud roll in and finally pack up the observatory by 22:31UT.
This is a continuation of My ‘Hidden Treasures’ sessions. Don’t worry about the stars – it was a bit windy at times.
NGC7008 It’s named the Fetus ( I think they mean Foetus) Nebula.
What a weird shape this is. While it looks oval, just to the South East is a darker lane that cuts through the outer shell towards the central star.
The PN has an inner shell that appears to have two brighter patches at the North and South ends. I assume these are lobes. There is an outer shell that extends to about 100 arc/sec and on the north side of this, there is a brighter patch that lines up with the bright patch in the inner shell. The outer shell is quite thin.
There is what appears to be a star embedded at RA 21: 00 30.81 DEC +54° 32 46.0 but Simbad says this is a knot rather than a star.
Simbad Entry is : PK 093+05 1 , misclassified PN: “probably knot in PK 093+05 2” (Kohoutek, 2001A&A…378..843K, Cat. IV/24)
The Kohoutek reference paper doesn’t really lead to anything specifically pertinent, but there is an interesting paper on spectroscopic measurements of these knots below.
SJM in his book, says that spectral observation of this and two other ‘knots’ are condensations expanding with the surrounding shells.