Observing Report 27/4/11

[barx1963 (Malcolm)]

After a few weeks of hectic activity due to other commitments, finally managed to write up some notes. More to come!

Observing Report 27/4/11

All observations made using Dobsonion mounted 305mm Newtonian reflector at f/5. Eyepieces use are 34mm Meade 4000(44x) 24mm Panoptic (67x) 13mm Nagler T6 (115x) or 13mm Nagler with Barlow (230x)

Charts - Uranometria 2000 (2nd ed.) Data derived from Uranometria (2nd ed) Deep Sky Field Guide (DSFG) with additional data from The Night Sky Observers Guide (NSOG) .

NGC 4902 Galaxy in Virgo
RA 13 01 00.2 Dec -14 30 49 Mag(V) 10.9 Dim’ 3.0 x 2.7 SB 13.0 Type SB(r)b I-II Early barred spiral with ring

From Alpha Virgonis (Spica) move 5deg to S to 69 Virgonis then 4deg to p to 53 Virgonis. A pair of mag 7 stars running NS lie 2deg to Np. A very faint pair forms a equilateral triangle with these 2 stars that points to p. Target os 30' p of this pair. Target forms a tight triangle (2-3' wide) with 2 double stars on its p side. Fairly small. Averted vision required to see, some mottling evident. Is a barred spiral, grows gradually brighter to centre.

Post Observation Notes. Image here http://spider.seds.org/ngc/ngcdss.cgi?obj=NGC!4902&r=13:01.0&d =-14:31&e=J2000&h=15&w=15&f=GIF&c=non e shows lots of structure which appeared as mottling. Was a little surprised I needed averted vision to see clearly for a mag 10.9 object.

NGC 4856 Galaxy in Virgo
RA 12 59 20.6 Dec -15 02 40 Mag(V) 10.5 Dim’ 4.3 x 1.2 SB 12.1 Type SB(s)0/a S shaped Barred Spiral

A triangle of mag 6.5 and 7 stars lies 1deg to Sp of NGC 4902. The 2 N stars point to f at target about 15' away. Fairly conspicuous with bright core and a bright "knot" on f side, possibly a foreground star.

Post Observation Notes. Not much detail was visible despite this being a fairly bright object. Image here confirms this impression http://spider.seds.org/ngc/ngcdss.cgi?obj=NGC!4856&r=12:59.3&d =-15:02&e=J2000&h=15&w=15&f=GIF&c=non e .

NGC 6139 Globular Cluster in Scorpius
RA 16 27 40.4 Dec -38 50 56 Total Vm 9.1 Brightest Star Vm 15.0 HB Vm 17.9 Diam’ 8.2 Conc Class 2

From Mu Scorpii a right angled asterism 1deg long lies 2.5deg to p. From this a group of 3 stars mag 5 lies 3deg to p. Target forms Sf corner of a large parallelogram with these. Small with a brightish core, some granularity at 115x but appears just beyond being resolveable.

Post Observation Notes. Also known as Dunlop 536, discovered by Dunlop May 13 1826 at Parramatta. DSS Image http://spider.seds.org/ngc/ngcdss.cgi?obj=NGC!6139&r=16:27.7&d =-38:51&e=J2000&h=15&w=15&f=GIF&c=non e shows the scattered stars around the central core that give impression that it nearly resolveable. Given brightest star is only mag 15, would make an interesting test for a larger scope.

NGC 6153 Planetary Nebula in Scorpius
RA 16 31 30.6 Dec -40 15 12 Diam” 24 Mag(P) 11.5 Mag(V) 10.9 Mag Cent Star 16.1

Lies about 1.5deg to Sf of NGC 6139. Forms S side of Diamond with 3 other stars brightest of which is about mag 9.5. Nice round glow, just non-stellar at 67x, easy at 115x and very prominent at 230x. Just a hint of colour. OIII filter brings out the glow. NSOG suggests dark annulus can be seen with averted vision but not seen at 230x however at 115x it is possibly seen.

Post Observation Notes. Image here http://spider.seds.org/ngc/ngcdss.cgi?obj=NGC!6153&r=16:31.5&d =-40:15&e=J2000&h=15&w=15&f=GIF&c=non e shows the annulus and the 3 nearby stars.

NGC 6192 Open Cluster in Scorpius
RA 16 40 20.8 Dec -43 22 00 Mag 7.2 Diam’ 9 No. of Stars 60 Mag Brightest Star 11.0 Type cl (Open Cluster)

Small faint Open Cluster. Fairly even with little concentration. Fills about inner third of FOV at 115x. About 30-35 stars of mag 10-11 are resolved with many fainter stars.

Post Observation Notes. Oddly the DSFG describes this cluster as have a highly concentrated core. My obs and the image here http://spider.seds.org/ngc/ngcdss.cgi?obj=NGC!6192&r=16:40.3&d =-43:22&e=J2000&h=15&w=15&f=GIF&c=non e do not bear that out.

Malcolm