EAA Observing Session : 20 September21/09/2023
Astronomy

Session Data

  • Date:  20/09/2023
  • Time:  19:28 – 22:20 UT
  • Seeing: II. Good – Slight
  • Transparency: II. Clear with some cloud
  • Temp: 11.2C,
  • Air Pressure: 998mb, 
  • Humidity: 93%, 
  • Dew Point: 10C, 
  • Wind Speed: 4mph
  • SQM:19.78 magn/arcsec^2

Scope: Altair 250mm RC f/5.3 Camera: ZWO ASI 183MM Pro, No Filter. Dark subtracted and Flat fielded.

Session Notes: 

North is to the top of the image in all these observations. I’m hoping this is going to make descriptions far easier to write.

NGC6210, HT78

At first glance this looks to be nothing more than an over exposed blob with a diffraction spike. It is, but after 5 mins I’m just starting to make out what looks like the spiral arms of a small barred spiral galaxy. Fortunately, the diffractions spikes are offset from the arms, so they are visible.

There appears to be a bright spot extending from the blob by 18 arc/sec just to the right of North and another about the same distance just North of West. At the tip of the Southern arm 20 arc/sec is another. If I tried to describe it, I’d say it looked like the nozzle of a garden sprinkler.

At 6 mins the blob is starting to become egg shaped with the narrow end pointing to the South West.

Image integration Time; 420 secs

NGC6712, HT95

This is really pretty

A small and very compact Globular cluster with a diameter of about 3.2 arc/min as observed. Its fairly circular, but there is a concentration of brighter stars in the South West quadrant. There is what appears to be a hazy mist, which is suspect is just the light from fainter stars within the cluster blocking out the darkness of the background.

Image integration Time; 420 secs

IC4756, HT93

This is one of SJM two for the price of one clusters. Except for me that is, as I have such a narrow FOV, I cannot see the other half, which is NGG6633.

I’m only seeing 34 arc/min at its widest in an East West direction, so I’m not seeing the whole cluster. Having said that, what strikes you immediately on seeing the first image is what looks like one twist of a double helix of stars, most of which are in an 8 to 9 mag range. It makes an effort to be symmetrical, but just doesn’t pull it off. Anyway, I liked the symmetry in what I could see here.

Image integration Time; 120 secs

NGC6633, HT92

This is the other half of the SJM HT92/93 cluster group. However, in this FOV I’m seeing most of Mellote 201 as well. Mel 201 and NGC6633 are pretty much entwined, and you wonder how the early discoverers didn’t just call this one large cluster on its own.

There is a general axis of 8 to 9th mag stars running North East and fanning out in width as they go towards the South West.

In the SW quadrant there appears to be the three tips of a three-leaf clover that is centered around RA: 18:26:55 Dec: +06°27’58”

In the NE quadrant Mel201 looks like a Question mark at its centre.

Image integration Time; 30 secs

NGC6781, HT18a

NGC6781 The Ghost of the Moon nebula seems quite an appropriate name. At first, I thought it was a circular smudge on the screen, which moved to the centre after platesolving.

After 5 mins of stacking this looks just like Police Commissioner Gordon’s Bat-signal searchlight that calls up Batman from his secret den in Gotham City. I jest you not.

Almost circular with a diameter of 60 arc/sec, the bat symbol is almost vertical running North South. The ring has a very thin brighter shell of material around its circumference, so does this suggest that this is the thickness of the shell at this point and that the bubble would look hollow.

The definition of the bat shape is helped by an ‘X’ shaped row of stars that cross at the centre of the expanding disk. There appears to be a star at the centre – presumably the progenitor White Dwarf- and Astroplanner labels this as 4UCAC 483-098452 at 15.91 mag. Simbad comes up with NVSS J191828+063220 — Radio Source.

Subsequent research tells us that we are looking at a bi-polar PN and viewing it through one of the poles that is directly pointing towards us. If we were to look at it side on, it would resemble something more like M27.

This was a really interesting observation in that it reminded me of what this could have looked like through and eyepiece and in order to make out all subtle details, you would have to spend time on it.

Image integration Time; 750 secs