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Old 18-09-2011, 08:27 PM
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Observations 20/8/11

And a few more from last month.

Telescope 400mm f4.9 tri-dob reflector
Eyepieces 28mm UWAN, 17,13,9 mm Naglers, Paracorr
Navigation: Night Sky Observer’s Guide (NSOG) and Uranometria

2200

Seeing very good, transparency very poor

IC 4725/Messier 25 OC in Sagittarius

90X Stunning cluster of many bright stars, looks 30’x20’ longer N-S with big dark lane running E-W across the middle, narrower in the centre as if the cluster has a waist. To the north-eastern side of the waist is a graceful arc of stars and to the east of this is a bright yellow star, which I imagine could be the lucida. Other interesting asterisms come of the waist to the south.

NGC 6645 OC in Sagittarius

135X An intriguing 10’ cluster of fainter stars with 2 adjoining circles of stars enclosing star-poor areas, making a N-S figure 8. A less distinct arc to the following side could give the impression of a clover leaf. A bright double sits at the southern edge. Sits within a busy star field.

Comet C/2009 P1 Garradd

135X The comet is quite bright with distinct nucleus close to bright star, the tail appears 15’ long and finishes at a nice little triangular asterism. Little coma preceding the nucleus.

NGC 7090 GX in Indus

175X A beautiful edge-on spiral in a field of bright foreground stars. There is an impression of a nucleus and a mottled appearance suggesting dust lanes. Elongated NW-SE with the nucleus more towards the NW end and a foreground star sits in the SE end. Looks good even in these poor conditions. Looks 7’x1.5’

NGC 7064 GX in Indus

175X More challenging in this murk than 7090, this is a distinct, thin edge-on spiral roughly E-W with foreground star to the north. Looks 3’x1’. Would be interesting to revisit in better conditions.

NGC 7083 GX in Indus

175X N-S Oval halo with distinct nucleus, faint impression of spiral arms, but this could well be my imagination. To the east is a pair galaxies in the murk. NGC 7096 follows and is brighter than ESO 107-44, from which it is separated by about 14’. Both could be face-on spirals but it is hard to tell under the poor conditions.
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Old 20-09-2011, 09:51 PM
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madbadgalaxyman (Robert)
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When the eye+brain sees an intermittent feature - is it real?

Paddy,

When you write "faint impression of spiral arms" and that this might just be your imagination, this illustrates a common problem with visual observations which are made at or near the extreme limit of the eye's sensitivity to low surface brightness diffuse light;
given that the eye/brain system's detection of an object is intermittent, at this low level of surface brightness, with a feature or an object flashing on and off, how to decide if an "observed" feature is really there or not?

In my bygone days of regular visual observation (I observed mainly galaxies and diffuse nebulae for some 26 years), I used a few techniques to help me decide if my eye/brain system's "detection" of a vanishingly faint object or feature actually corresponds to something in the real universe rather than just something that my brain has made up:

(1) I would keep observing the faint apparent object or feature for a prolonged period of time, and I would count the number of times that I could see it, even if it only flashed on for a second each time I did see it. If I could glimpse the apparent "feature" at least 6 times, I would estimate a high probability that the feature is actually real, even if afterwards my tired eye could not see it any more.

(2) Given the notorious "suggestability" of the human brain, when it responds to images from the eye which are at the extreme observational limit (e.g. the canals on Mars), we do not want to be in the position where a feature is deemed to be real by the observer simply because it was briefly "glimpsed" or perhaps only imagined to exist, due to the tendency of the eye+brain system to believe it has seen something despite an absence of hard evidence.
So what I do is to try to negate this obvious bias of "really wanting to see something" which then causes me to "see" something which does not exist in the real universe;
I try to convince myself that I am not seeing the apparent object which is "seen" at the extreme limit of detectablity (thereby setting up a bias in the opposite direction), and if I still see an object or a feature, despite trying hard to convince myself that it is not there, the observation is much more likely to be an actual detection of light from the object than merely my imagination playing tricks.

(3) Come back to the object later on in the night, or wait for that "perfect" night, in order to confirm or deny an existing tentative observation.
There were many cases in which I had to repeatedly come back to an object in order to figure out what I was seeing (or not seeing) ; for instance it took me a very long time with a 10 inch Newt to figure out the complex structures observable within NGC 1313 and NGC 6744

(4) Rest the eye and body and mind, at various times during a prolonged and arduous observing session. A tired eye+mind+body is not a good instrument for detecting faint features in galaxies - so go and have an cup of coffee, or lie on an air mattress with binoculars...which gives the eye the opportunity to relax. When I observe, I always have some periods with binoculars, lying on my back, between the periods with the telescope....it refreshes mind and body and eye, most amazingly.
You see more afterwards!

[of course, other Deep Sky observing tricks include averted vision, and moving the vanishingly faint object just slightly (the eye sometimes responds more strongly to a moving object) ]

Last edited by madbadgalaxyman; 20-09-2011 at 10:06 PM. Reason: correction
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Old 20-09-2011, 10:49 PM
Rob_K
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Great report Patrick, and good discussion Robert!

Quote:
Originally Posted by madbadgalaxyman View Post
So what I do is to try to negate this obvious bias of "really wanting to see something" which then causes me to "see" something which does not exist in the real universe;
I try to convince myself that I am not seeing the apparent object which is "seen" at the extreme limit of detectablity (thereby setting up a bias in the opposite direction), and if I still see an object or a feature, despite trying hard to convince myself that it is not there, the observation is much more likely to be an actual detection of light from the object than merely my imagination playing tricks.
Quite hard to do (consciously tricking yourself) but still useful no doubt. For really faint objects on the limits of detectability (rather than faint details in galaxies) where I might get odd flickerings of something in the position, I usually repeat the process in another or even several parts of the field. You quite often get a similar response. Sometimes when you move your eyes back to the target position you get a much stronger response that can be held in averted vision even if intermittently, almost like the exercise sharpened your vision. But if I get the same flickerings of something (all too often!), I'm fairly satisfied that I'm not seeing anything other than a trick of the eye. You really have to hold it, even briefly.

Spending time is essential, and movement helps greatly. Provided your eyes are fully light-adapted, I find that coming back to the field later on in the observing session doesn't help all that much unless there is a change in transparency, because you have to pretty much repeat the teasing-out process all over again. May as well spend quality time first-up.

Cheers -
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Old 21-09-2011, 07:57 AM
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Why no standard procedure for visual deep sky observation?

Very interesting post, RobK, showing some divergence of opinion between two people, both of whom have done a lot of visual observing.
This divergence does illustrate the fact that there may be important discrepancies between experienced observers, as regards the optimal techniques for seeing diffuse and low surface brightness features and objects.

Other types of observational science have adopted standardized techniques, and I believe that the field of visual deep sky observation would benefit from the same type of standardization......let's get all of our worthwile visual observing techniques together into one list, and then make up a really detailed "how to" for visual deep sky observers.
(e.g. averted vision techniques have been discussed at length, in some forums, yet this process is still poorly understood by many observers)
________________________________

You are right that a single longer detection of the faint object or feature helps to cement the case for it being something that exists in the real universe.
I have had more success than you have with coming back to the same object later in the night, in order to see if I can detect anything more than I did at first (or maybe detecting less than I did at first) .

My point about using binos and an air mattress to relax the mind and body , in between sessions at the telescope, is an obvious point, yet this technique is not always adopted by visual deep sky observers, despite the fact that it noticeably increases the observer's ability to detect faint features when she/he goes back to the telescope after the observer has spent a few minutes on his back using the binos.
___________________________________

When I was in my prime for visual observation, I found that two family-sized chocolate bars plus a packet or two of Tim Tams, per every night of observation, did wonders for my energy levels (ha ha)
(it's a wonder that all that chocolate didn't poison me)

___________________________________ ___
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Old 21-09-2011, 09:57 AM
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Quote:
Originally Posted by madbadgalaxyman View Post
When I was in my prime for visual observation, I found that two family-sized chocolate bars plus a packet or two of Tim Tams, per every night of observation, did wonders for my energy levels (ha ha)
(it's a wonder that all that chocolate didn't poison me)
Chocolate can do funny things to my vision, more a coffee-&-cigarettes person here...

Good idea to list all the techniques Robert but personally I'm against any sort of 'standardisation' because it implies there is some importance to attached to it. Just don't see it I'm afraid. No ordinary deep sky visual observer is going see anything through any telescope that is not known about in the raft of objects we are able to observe, and for people involved in things like comet and variable star visual observing, the important observing protocols aren't related to 'advanced techniques'.

For me, it's just relaxation and enjoyment, and any way is a good way if you enjoy and benefit from it. KISS!

Cheers -
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Old 21-09-2011, 07:35 PM
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Paddy (Patrick)
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Thanks Robert and Rob for your response and especially for your great insights into observing. There's a lot there to digest and try out. I find it interesting that I naturally give my visual system a break by just looking at the sky naked eye for patches in the session (and star hopping does the same I think by changing the tasks) but it would be interesting to make that more formal as you've suggested, Robert.

I suspect that a lot of folk are not reading this thread and they will be missing a very interesting discussion and some very useful tips. I think it would be great if there was an article or at least a specific thread on the topic.
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Old 21-09-2011, 10:53 PM
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I totally agree, Paddy, that a new thread could be started in the "Observational and Visual Astronomy" section, perhaps with a catchy title such as "Best visual Observing techniques for deep sky"

Is there any easy way to transfer most of this thread to the Observational and Visual Astronomy forum?

Many of us have developed "tricks and techniques" to enable us to better see those vanishingly faint HII regions and galaxies and other diffuse objects, yet it seems clear to me that some of these techniques are not as widely known as they ought to be.
Some of these techniques are seemingly quite trivial, such as my observation that using binos (when lying down) maintains observer stamina and relaxation during a long observing session, while also increasing dark adaptation. Yet, deeply technical discussions of things like the response of the eye's rod detectors and the spatial distribution and density of the rods on the retina, are also very relevant to people who want to improve their deep sky observing skills.

Oddly, at present I am only doing a handful of visual observing sessions per year (galaxies databases & catalogs & scientific papers are of more immediate interest), yet for many years in the past I was fanatically interested in any tips and techniques which could increase my ability to conclusively detect faint features in diffuse objects.
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Old 22-09-2011, 12:36 PM
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Made the best of the poor transparency there Paddy NGC 7090 is a nice object indeed.

Interesting dicussion re extremely faint objects and their visibility. It's something I definately consider when observing. I won't confirm a sighting until I've atleast seen the object materialise a number of times (maybe 5-10), and I'll use field stars and/or other brighter objects to make sure it appears in the same location every time. If that's the case, then yes it's a hit.

I use a black shroud over my head, it really helps with observing at the limit of vision and kills any stray reflection on the eyepiece etc that may be mistaken for that faint dust mote and ofcourse it allows you to observe without cupping your face with your hands or having to perform other distracting gymnastics to fend off stray light. Also keeping both eyes open (and covering the unused one with your hand) saves you from unnecessary strain.

As has been suggested taking regular snack breaks is a must and helps you relax and recharge ready for the next extremely faint galaxy.
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Old 22-09-2011, 02:02 PM
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Great observations Paddy,

Very interesting disscusion.I have been doing some observing lately(I Will post them soon).

M57's central star is apparantly magnitude 15 and at low power i keep thinking that I can see the central star but upping up the power makes the star dissapear.I am not sure what is the cause, a physcological problem or power related problem.

Also the nearby galaxy Ic 1296(mag 14.8) seems to come in and out of view,Phychological or seeing?

I really don't know.

Cheers Orestis
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Old 22-09-2011, 03:43 PM
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Quote:
Originally Posted by orestis View Post
Great observations Paddy,

Very interesting disscusion.I have been doing some observing lately(I Will post them soon).

M57's central star is apparantly magnitude 15 and at low power i keep thinking that I can see the central star but upping up the power makes the star dissapear.I am not sure what is the cause, a physcological problem or power related problem.

Also the nearby galaxy Ic 1296(mag 14.8) seems to come in and out of view,Phychological or seeing?

I really don't know.

Cheers Orestis
Increasing magnification helps with faint stellar objects and is certainly beneficial for tiny faint galaxies. This is because it has the effect of darkening the background sky increasing contrast. Recently I was observing Uranus and Neptune and their moons were easiest seen at the highest power I could use within seeing limitations.
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Old 22-09-2011, 09:07 PM
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Thanks Sab and Orestis.

I think the ideas on more sensitive and accurate observing really do deserve their own thread, so I'm going to start one in the main observing forum and refer to this thread, but it would be great if the Roberts and Sab could put their thoughts into the new thread as well and we can keep it all in one location with whatever other gems come. I don't know whether as Robert suggests posts can migrate, but someone might suggest how in the new thread.
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Old 22-09-2011, 10:09 PM
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Very interesting report and discussion Paddy.
I'm a bit behind in my reading and your new thread pointed me here I look forward to more little gems.
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Old 22-09-2011, 10:27 PM
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One thing I've read so far that is being hinted at is what I call "light saturation" of our eyes. We typically sit on an object, and as the observation time elapses we begin to actually see less in the object than we noticed at the start of the observation. We are not imagining this. What is needed here is to restimulate our eyes. This is somewhat akin to how our nose looses its sensitivity to a particular odor when exposed to an odor for an extended period of time.

Another part to this is how our eyes are made to detect motion. Here's an example: You're looking across a peaceful valley. We see nothing moving, other than a few leaves on the trees (due to the breeze). Unconsciously our eyes begin to dart around, looking for movement (from a possible threat). We spot something out of the corner of our eye, a rabbit shooting off from a stand-still - we didn't see it at first even though it was in plain sight, as it wasn't moving, and the sudden change in light conditions, small as they were, was instantly picked up by our eyes when the bunny moved.

Where I'm heading to here is that a still, unmoving telescope is our biggest impediment. Our eye (or eyes if you're using a bino viewer), darts over the image the eyepiece presents. Low light quickly saturates the rods in our eyes, and we no longer see as much detail.
Solution: give the scope a little tap to set off a vibration, and all of a sudden our eyes begin to see detail! The induced movement restimulates the natural reactivation mechanism in our eyes.

This is something that I had noticed for many years, but wasn't aware that it was of the physiological reason behind it until it was explained to me. I had struggled on occasions to spot very faint objects at times, even though the charts said the object SHOULD be there. Yet, I only noticed it when there was a brisk movement or vibration induced in the scope, otherwise the object seemed to be totally invisible.

This is one reason why I've decided not to motorise my dobs. The constant shifting of the scope I actually now find is most benificial to my productivity.
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Old 23-09-2011, 08:49 PM
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Thanks for the interesting post, Alexander,

In visually observing a faint galaxy or faint HII region, or observing a faint feature within a galaxy or HII region, I would probably do a combination of the following things:

- looking fixedly, just to one side of the target object, while concentrating on the object itself, for 5-10 seconds, thereby allowing the exposure time of the rods to be used, and thereby allowing an image to build up.
- moving my eyes randomly and rapidly around the field, in order to relax or reset them
- looking fixedly just to one side of the target object again (but looking at the opposite side of the object to the side I looked at first), while still concentrating on the object itself. (again, for 5-10 seconds)
- looking straight at the object, for comparison with the views that I get using averted vision
- moving the telescope, just a very little, from time to time (as mentioned in mental4astro's post), which can make the object more obvious.

I repeat all of these steps when I observe a vanishingly faint Diffuse object, often repeating them many times, and I find that I do gradually build up a better idea about the morphology of the "very very faint object" in the eyepiece. This seems to be an additive process, and the various glimpses that I get of the object (or of features within the object) can be used to build up a better picture of it.
I have been known to persist for up to one hour on a single object, at which point my eyes are thoroughly fatigued.

If I am not sure whether or not I have seen something, I resort to some of the stratagems in my previous post within this thread (title: "When the eye+brain sees an intermittent feature - is it real?).

I think that this is my usual procedure when observing low surface brightness galaxies & very faint nebulosity...... but some of it has become very instinctive, so I will go to the telescope and check if this is exactly what I do.

Let's do some experiments, folks, and find out which procedures work best when we are at the eyepiece!
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Old 24-09-2011, 06:29 AM
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Robert,

Your observing method is most thorough! Uncanny too how my own method has developed similar to yours. BUT what I hadn't done was attempt to exploit more of the rod-rich areas of my eye. I've settled into my own pattern, but you've inspired me to attempt a new stratergy.

Having an observing stratergy that is based on understanding the physiology of how our eyes work is probably the best way of making the most of our obseving time. The flexability in developing your own stratergy is the key here too. What I hadn't mentioned was the crucial importance of averted vision in the physiology. It will be a most interesting thread if Paddy succeeds in getting a sticky on this going. Most interesting.
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Old 24-09-2011, 08:27 AM
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Hi Alex,

Yeah, I was passionately interested in the issue of how best to detect diffuse & extremely-low-surface-brightness objects and features, for the 26 years that I was a regular visual observer. So, I kept my ears open for information about the retina, and I tried various things.
(I only observe 3-5 times per year at present. These days, I specialize only in the morphologies and properties of galaxies)

I think that I have described exactly what I do when I am trying to see low surface brightness nebulosity or galaxies, at the extreme limit of the eye's abilities, but it has become somewhat instinctive - so I need to go to the telescope and check that this has been my exact procedure.

Honestly, I don't know whether this is the optimal technique or not, but it worked for me, because there were some observations that I made in the 80s and 90s that represented the "state of the art" at the time, e.g. detecting the brightest portion of Barnard's Loop in 10x50 binos.
It also helped that I had young eyes...I think that we may lose some sensitivity as we get older.

cheers, Robert
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Old 17-02-2012, 05:52 PM
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Breathe!

One thing which I learned from distance shooting is to breathe well. If you breathe shallowly or even worse, hold your breath the sensitivity of your vision, which is very dependant on the oxygen level in your blood disappears. Some people tend to hold breath/breathe shallow unconsciously when looking in any kind of eyepiece so as to reduce the movement of the head. I have seen a crystal clear black target dot fade to white between breaths when looking down an open rifle sight. A quick search turned up this hypoxia related information:

Visual sensitivity at night is decreased by 10 percent at 1,500 m (5,000 ft) and by 30 percent at 3,000 m (10,000 ft).

This relates to a sudden change in air pressure rather than someone who is acclimatised to living well above sea level- similar effect to holding ones breath I should think.
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