Blog for Friday 25th Sat 26th and Sunday 27th May 2012
With the shortest night fast approaching a dark ‘astronomical’ sky is a short affair! With a rare run of hot sunny days & clear nights upon us I needed to modify habits. For me this means early to bed grab a few hours sleep then arise again at around midnight for a few hours of observing until the pre-dawn sky brightens. I would need these opportunities to catch up with the considerable number of Hickson compact galaxy groups around Bootes, Serpens and Hercules which are well placed at this time of year.
OK I have set the scene so we start with Friday night into Saturday morning, up and with a mug of tea in hand this is a true ‘brew & slew session’. First stop off was actually a distraction! I was intending to sketch NGC 4485/4490 the Webb society galaxy of the season in Canes Venatici, also known as the Cocoon galaxy and ARP 269. I star hoped up to CVn via Virgo when I spotted M106 in Canes Venatici on my planetarium software, hmmmm I though, I don’t think I have sketched that? I went through my Messier file and indeed that slot was empty. I locked onto the Messier galaxy and brought it up on the monitor…..Wow it was bright and big! I could have done with using a focal reducer but I didn’t have the time to mess around M106 is a large and exciting galaxy the Watec camera and big mirror really did pulled out masses of detail and structure, quite wonderful! See my sketch here
Next I did catch up with NGC 4485/4490 as I said above this too is in CVn the constellation of the ‘hunting dogs’. A very exciting pair of interacting galaxies 4485 being the smaller and looking like it is having the stuffing pulled out of it by larger 4490, both are actually spiral and were discovered by William Herschel on Jan 14th 1788. It is actually NGC 4490 mag 9.4 which is referred to as the ‘Cocoon galaxy’. See my sketch here
Finally I did get a Hickson! By now it was well into early morning of the 26th HCG 74 was a tough observation there are 5 members of this group in Serpens which is not the most exciting visually members being small, faint and spaced out. The (E) member is tough at mag 18.2! See my sketch here
Time to go back to bed and try and sleep, that is tough too ;¬)
Saturday night into Sunday morning, brewing and slewing again and off in search of more faint smudges in Serpens. I picked up where I had left of that morning, starting with the next on the list HCG75 and although after midnight local time it was before 00.00UT so technically a “Double Ender” for meJ. Right back to the observation, HCG 75 isn’t visually too exciting, 5 members all tiny ranging from high mag 15’s across mag 16’s, with a centrally placed PGC 54803 being both largest and brightest at mag 15.7. Not to grumble, another one down and a pigeon step closer to the 100th! See my sketch of HCG75 here
Next up we are onto HCG83 across towards Ophiuchus but actually one of the 3 Hickson groups in Hercules. This group I would say is the toughest I have observed to date, and I have seen a very commendable visual observation with a 22” F4 under a pristine sky, from my perspective I suppose you could say it was straight forward enough if you know what is what! But discerning the members from being anything else but stellar was very difficult, I dwelt on this group for an hour plus cross referencing tiny bright spots on the monitor with maps and CCD images in my reference material, ascertaining what was a star, a galaxy of just back ground noise on the monitor screen, I had chilled the camera down for a few hours in the refrigerator to keep the noise and hot pixels to a minimum on such a warm night, I’m glad that I had otherwise I may have missed off some of the very faint members! All members of the group are designated PGC 58559 A-E so 5 members in total, (A) being mag 15.8 and (E) being 18.9. I won’t say anymore as I wrote a few notes detailing each member and my thoughts so I will let both b&w sketch see here and the detail sketch see here speak for themselves!
Onwards and upwards, sticking in Hercules I push onto HCG81 closer in the direction of the well known Key Stone asterism that characterises Hercules. After HCG83, 81 appeared bright and obvious although on paper it isn’t, it jumped out at me on the monitor screen, less stars in the field for starters certainly helped. HCG 81 is a 4 galaxy group arranged in an arc, almost like a paw print, members are designated UGC 10319 (A)-(B), take a look at my sketch here
OK that is 2 out of the 3 Hercules Hickson’s, but it’s the weekend so I intended to push onto the 3rd, HCG82 which lies just to the west of the Key Stone. However my eye was caught by a planetary nebula showing up in my software within Hercules, IC 4593 (white eyed pea) is small PN catalogued at 15×11 arc seconds although most observers consider it to be smaller, bright, the usual fuzzy stellar jobbie at low powers, I confirmed this by doing a visual through the 6” at 70x, I wanted to sample the colour, no filter, to me it looked blue grey but other have stated, greenish, I won’t argue my dark adaption wasn’t that good! Using a x2 barlow lens before the camera to increase the image scale, I played around for some considerable time with focus, camera settings and monitor setting before I got the best image in terms of detail and minimising ‘burn out’ due to the brightness of the object. The central star was easy, the shape was circular, a small ring and when I got things just so, I could see extensions in the form of ansae extending NW & SE, a very nice little planetary that was worth the considerable effort to get presented at its best. See my sketch of IC 4593 here
And so to bed as dawn broke on a warm Sunday.
Here I am out again at 23-00UT midnight on Sunday night so another ‘double ender’ I’m eager not to spend too long outside, I have to be up for work at 6am local time.
I go straight for Hickson 82 which turns out to be the most interesting of the 3 Hercules groups, the members all contrast in shape and size. The 2 main member galaxies (a) NGC 6162 & (b) 6163 form a pair of round eyes, the left slightly fainter showed a hint of spiral arms with my set up, (c) member NGC 6161 is a little gem, looking like an exclamation mark with a star on its southern tip, I was able to pick out a dust lane bisecting it e-w, last but not least (d) PGC 58231 is a tiny but very recognisable edge on. See my sketch of Hickson 82 here
I have time left to push on into Lyra and go for planetary nebula NGC6765 which is a Webb Society object of the season. This isn’t my first observation of this interesting and quite unusual nebula, but I think at the time of writing that it may be the first that I have made with the 505mm mirror. Anyhow without further ado, this is a small nebula with a central elongated region resembling a segmented bacterium under a microscope in my eye; there are arcs of material curving to both east and west but more noticeable to the east, so the overall appearance is somewhat ‘keyhole’ like. Please take a look at my sketch of NGC 6575 here
That’s all folks, I hope to be back soon with more exciting objects from outer space! Dale