Recently Browsing 0 members
No registered users viewing this page.
Date: Sunday 1st March 2020. (2240-0220am)
Scope: 20” f3.6 Lukehurst Dob with Paracorr (fl = 2089mm & f4.1).
Night Vision: PVS-14 with Photonis 4g INTENS.
Eyepieces: Plossl 55mm (f2 x38), Panoptic 35mm (f3 x60), Panoptic 27mm (f4 x77), DeLite 18.2mm (f5.8 x115).
Filters: Baader 610nm Red Filter
Wow, it’s already March and I’ve just completed my first real session of any note in 2020! The weather in the UK has been pants since Christmas. I have managed a couple of two hour dashes between the clouds but that is not enough time to really get into a session and do any real observing on any more than a few objects so I have mainly been observing the more famous and brightest night sky objects.
Galaxy season is here!
Yay, my favourite observing season is here. With all this down time, I at least had an observing plan to follow when the opportunity finally came. I had created observing lists in Sky Safari of the Hickson and ARP catalogs.
Making a start on the Hickson catalog with Night Vision.
There was a 39% moon in the West so I had to deploy a Baader 610nm Red filter to the front of my Paracorr2 to remove the unwanted moonlight from my view.
On the first object, I tested out all the eyepieces listed above to see which produced the “best” view. There is a trade-off with night vision devices of image brightness and image magnification and I wanted to identify the best eyepiece option up-front as I intended to attach my eyepiece heater tape and then stick with the one eyepiece for the session.
I settled on the Panoptic 35mm as my chosen eyepiece as it was giving decent image brightness resulting in more galaxy halo and the magnification (x60) was enough to provide something to see from these tiny objects.
Hickson 37 – I could see three galaxies in a row close to two field stars. One galaxy was a longer edge-on and one had a bright core with faint halo. I found the fourth group member nearby just the other side of a field star although this one was a challenge to hold in vision for long. The final galaxy was glimpses occasionally with a real effort and concentration needed.
Hickson 44 – Two small bright galaxies were immediately obvious, I soon located a third slightly separated galaxy of mid-brightness out in front. The final galaxy was the faintest of the four and was sited at 90 degrees to the side. All four galaxies were easily seen in direct vision.
Hickson 46 – This group was hard to locate initially then I spotted two cores appearing close together in the field of view. After letting my eye settle in the other two galaxies appeared one on either side of the first two.
Hickson 47 – Two cores were immediately obvious in the fov then one more emerged lower (near a field star). I did get glimpses of the fourth member which was in close to the third galaxy staggered to one side.
Hickson 38 – Another group that was tough to find. Found just above left of two bright stars. Time reveals three galaxies in a triangle formation. The lower galaxy was the easiest with a nice halo. The upper two were smaller and fainter.
Hickson 36 – The toughest so far! I found a possible very faint patch just below 6 stars. It looked like two groups of three galaxies but looking at images this morning then this looks incorrect so this goes down as a fail.
Hickson 35 – Found inside a triangle of field stars. Three galaxies easily seen in a flat triangle formation. There was a possible fourth galaxy glimpsed to the left which was fainter.
Hickson 41 – Two galaxies easily seen (one has a core and halo). The third was tough and appeared just under the fainter of the first two. No sign of the fourth member.
Hickson 60 – A small patch is easily seen in the fov. One core dot is seen within the patch off–centre.
Hickson 56 – This tiny group is located next to two much larger and brighter galaxies (NGC 3718, 3729) that overpower your vision as you reach the eyepiece. Once I was settled on my actual target then I saw two tiny bright galaxies first. Then the third was seen slightly separated to the RHS. Then one appeared LHS fainter giving a 3+1 appearance to the group.
Hickson 55 – The small patch was quickly located in the fov. I could see two dot cores appearing on and off within the patch but not much more.
Hickson 49 – not found.
Hickson 61 (Box Galaxies) – A nice sight. Three bright galaxies make up three corners of the “box”. A fainter larger galaxy sits at the other corner. The two brightest galaxies were at the top side. The bright lower galaxy has a halo.
Hickson 51 – Five galaxies are easily seen in the fov, appearing as 3+2. The galaxies appeared well spaced but were small.
Hickson 57 (Copeland Septet) – A very nice galaxy group! I could see 7 galaxies appearing as 3+3+1 formation. All easily seen.
Hickson 53 – I saw three galaxies in the fov in a 1+2 formation. The fourth member (off to the right) was not seen.
Hickson 52 – Two galaxies were easily seen. Another galaxy is glimpsed intermittently near to the second galaxy with time at the eyepiece.
Hickson 59 – 3 of 5 galaxies seen. Two are bright and easily seen. The third appeared at a right angle to the first two with the gain turned up.
Hickson 58 – Four galaxies are easily seen in a 2+2 formation. The fifth needed further exploration but clouds starting passing and my session was cut off in its prime!
I make that 18 Hicksons attempted last night which seems like a good start and I am pleased with that.
Most of the observations were taken with the Moon up so it will be interesting to try them again on a new moon to see if more can be seen…
It was great to be back outside after nearly two months of slim pickings!
Some Technical Background (Voluntary reading!).
This section is added for anyone wondering why I was only using x60 magnification with my setup and maybe “more would be seen with greater magnification?”.
While that would be true with traditional observing, night vision is best used with eyepieces with large exit pupils as the more light you get into the device then the more light it has to work with. Longer focal length eyepieces (greater than 27mm) also have a side-effect of increasing the effective focal ratio of your telescope system (as far as the attached night vision device is concerned) and as the NVD works at f1.2 then the closer we can get to that speed the better the results will be.
So the facts are that the 55mm Plossl with always show the brightest view possible with the most galaxy details possible seen within that view.
But when tiny objects are tightly packed then you may need more magnification to separate them (this is usually true for supernovae hunting for example).
But as you increase magnification and decrease the exit pupil/effective focal ratio of the system then galaxy detail will be lost from the view. I only ever view galaxies where I hope to see the spiral arms with the 55mm Plossl as I want maximum brightness and fastest effective focal ratio.
Celestron 9.25 at f6.3, SW EQ6R pro, Canon 550 D modded
The galaxy group Hickson 44 in Leo. This is based on 29 x 240 s, plus bias and flats.
Hickson 44 in Leo:
There are some other galaxies near by, some of which are names in this overlay from Astrometry.net:
Overlay from Astrometry, naming the other objects:
The main ones are NGC 3190, NGC 3185, NGC 3187 and NGC 3193. NGC 3190 has a well defined dust lane. NGC 3187 is a barred spiral galaxy with two arms. NGC 3193 is an elliptical galaxy.
The light captured by my camera last night left these galaxies just after the extinction event killed the dinosaurs on Earth.
From APOD: Galaxies, like stars, frequently form groups. A group of galaxies is a system containing more than two galaxies but less than the tens or hundreds typically found in a cluster of galaxies. A most notable example is the Local Group of Galaxies, which houses over 30 galaxies including our Milky Way, Andromeda, and the Magellanic Clouds. Pictured above is nearby compact group Hickson 44. This group is located about 60 million light-years away toward the constellation of Leo. Also known as the NGC 3190 Group, Hickson 44 contains several bright spiral galaxies and one bright elliptical galaxy on the upper right. The bright source on the upper left is a foreground star. Many galaxies in Hickson 44 and other compact groups are either slowly merging or gravitationally pulling each other apart.
This image is based on 19 x 300 s , plus flats and bias. It shows a LOT of galaxies, in a grouping called Abell 1367. In this image you are looking at part of one of the biggest structures in the Universe, the Great Wall.
The Leo Cluster (Abell 1367) is a galaxy cluster about 330 million light-years distant (z = 0.022) in the constellation Leo, with at least 70 major galaxies. The galaxy known as NGC 3842 is the brightest member of this cluster. Along with the Coma Cluster, it is one of the two major clusters comprising the Coma Supercluster, which in turn is part of the CfA2 Great Wall, which is hundreds of millions light years long and is one of the largest known structures in the universe.
The overlay from Astrometry gives some of the galaxies visible in the image.
By Martin Meredith
Is it possible in near real-time observing to capture photons that set out in the first billion years of the life of the universe? Under current estimates of the age of the universe and its expansion, any such object will have a redshift of at least 5.7.
While preparing the indices that will accompany the forthcoming deep maps release, I spotted a possibility listed in the Veron catalogue , which goes under the unromantic name of SPIT J17210+6017 after the Spitzer First Look Survey. This quasar has an estimated redshift of just a fraction under 5.8, corresponding to light seen from a universe just 0.97 billion years old. A listed V magnitude of 20.6 makes it a very challenging target for my alt-az mounted 8" scope.This object lies in the rich galaxy fields in the centre of Draco, more or less equidistant between NGC 6361 (Arp 124) and VV 1840, the former being my starting off point last night before hopping down to identify the correct field for the quasar. With a sky of SQM 20.3 I went for 30 second subs.With some wishful thinking, the quasar started to appear after live stacking of 6 or 7 subs, but by 10 it was reasonably certain:I continued stacking just to be sure. Here are closeups at 10, 16 and 28 subs, compared to the DSS image.There are even more distant quasars listed (this doesn't quite make the top 20 in the Veron catalogue) but most are significantly fainter (but still worth hunting down!).Thanks for looking, and a big thanks to Paul for the robust live stacking in LodestarLive that makes this kind of thing so much fun.Martin Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010), accessed as Table VII_258_vv10 on VizieR.
By Martin Meredith
Here are some bright nebulae I observed last week, all using 15s subs live stacked in LodestarLive. Filters are probably necessary to get the best views of some (or all) of these objects, but I wanted to see what the unfiltered mono camera was capable of producing.
First, NGC6888, the Crescent nebula. I was happy to capture at least part of the nebulosity but was fighting a 75% moon which didn't set for 2-3 hours after this shot (SQM 19.3 skies). But what struck me most watching it build up is that the beauty of this field is not simply the wraith of nebulosity embedded in a rich star field, but the 4 or 5 brighter foreground stars, of which 3 appear as doubles. Two are catalogued in the Washington Double Star list. OS401 (Otto Struve) has components with mags 7.2 and 10.7, separated by 13.8". The pair SLE 955 has mags 8 and 13 with a 14.9" separation. Also labelled are a couple of other members discovered by SLE (anyone know who this is?). Pair 956 is an almost equal pair (11.9, 12.8) separated by 9.9", while pair 965 is an equal pair of mag 12.5 stars with a 7.5" separation. V1770 Cyg is variable but not listed as a double.
Taken a couple of days earlier with a setting moon, this is a shot of the Cocoon, the first time I've seen this object and not the last. It really is a spectacular sight with its inner sanctum revealing one bright and many faint stars. It appears to be surrounded by obscuring dust too. Also marked is an unexpected find: a faint background galaxy (PGC 167593 mag 18.2). It must surely be quite rare to see a galaxy in this part of the sky given the density of stars and dust?
Next, part of the Western segment of the great Veil supernova remnant. I've observed this visually with an O-III filter and it looks superb, so I was interested to know what an unfiltered view looks like with the Lodestar. Both arcsinh and x^0.25 scaling produced good views of the Veil.
Next, some nebulosity surrounding two pairs of bright stars (looks like a cat's face to me) and an open cluster, Dolidze 8, in Cygnus. These are known as Van den Bergh 132 and 131.
Here's part of the "War and Peace" nebula (NGC 6357) in Scorpius. I was really struggling with this low target to bring out the fainter extensions while keeping the stars from too much bloat, and haven't really succeeded. I think it is worth a visit with a filter and a wider FOV at some point.
Finally, M17, the Omega Nebula in Sagittarius. This is a full 4 magnitudes brighter than War and Peace, and it shows! This reminds me of a cloud underlit by significant light pollution.
Note that in many cases these are quite long stacks, but they accurately represent the end product of a real-time observing experience during which the image continually improves with 15s updates. For me nowadays "total exposure length" is almost unimportant: I observe for as long as I like (usually 15-20 mins per target including finding and framing). None of this would be possible without robust live stacking.
thanks for looking
By Martin Meredith
SHK 10 is the second most galaxy-rich of the 377 Shakhbazian compact groups (*), packing an astonishing 32 galaxies into a space of little over 6 minutes of declination. On the other hand it is rather faint: its brightest member shines at mag 17.7 from a distance of around 1.7 billion light years. SHK 10 can be found centred at [14 10' 56.1" +46 15' 54.7"] a degree or so from mag 4.2 lambda Bootis heading towards the border with Canes Venatici (chart BOO/5769 in the Pretty Deep Maps collection). Here's a screenshot showing the locations of the galaxies, numbered using Shakhbazian's scheme.
For me, the challenge of the Shakhbazian groups is seeing how many members can be pulled out using near live viewing techniques -- literally seeing more and more of them appear on the screen as live stacking does its magic. To give a flavour of the live experience, I've prepared a cropped animated gif showing the progress as more subs come in: 1, 2, 4, 8, 16, 32 and 64 in total. This was also a test of fast stacking so the subs themselves are short, at 10s. Note that this is all live stacked in LodestarLive v0.12 and not post-processed in any way apart from rotation to match the chart. I retained the same brightness and contrast settings throughout, and used the ^0.25 compression mode. The group is in the central third of the shot.[Edit: animation appears not to work yet … here's a temporary dropbox link (0.5M)]Noise is greatly reduced by stacking, revealing the galaxies.Here's the last frame (64x10s stack) in full. Note the super-thin galaxy at top-right. This is mag 16.3 UGC 9066 at a distance of nearly 400 million LYs. Here I've blown up the central portion and labelled the constituents. There are a few obvious stars amongst this group and also some interlopers -- things that look like galaxies but are not listed by Shakhbazian. Checking the SDSS image using Aladin these are definitely galaxies. Whether all belong to the same physical cluster is another question. As recently as 2012 there were only 13 spectroscopically-confirmed members.The ones I've failed to split are 19/20 and 8/24, though the latter actually appears to be a single edge-on galaxy in the SDSS image.Details: SQM 20.2, windless, no moon, around 50 degrees up. Skywatcher Quattro 8" f/4, Lodestar mono X2, LodestarLive v0.12, no filters, AZ-EQ6 mount in alt-az mode. CheersMartin(*) The title goes to SHK 40 in Pisces, a relatively-bright 60-member group also known as Abell 193.