Posts Made By: Inge Skauvik

I found the recent thread about NGC1999 quite interesting, because this is an example of an object normally considered to be rather featureless and boring where higher magnification can reveal some interesting detail.
Until recently I also considered M43 to be a quite uninteresting patch of nebulosity, but observing it from La Palma I found that it contains quite a lot of interesting structure.
Do anybody out there know about other examples of such nebulae? I admit that I mostly use low magnification on diffuse nebulae, and there are quite a few patches (perticularly in the winter sky) which I never have paid much attention to.

Inge S

The objective of this post is not to provide a physical or scientific classification of planetary nebulae, but rather to encourage observing these facinating objects.

Planetaries vary greatly in size and surface brightness, and also - to some extent - in shape.

From the impression I get of the nebulae through the eyepiece I have made myself seven main groups. In most cases I find it easy to readily identify the right group for the object I observe, but certainly there are grey zones, and sometimes one object can belong to more than one group.
Observing these objects with larger telescopes will probably make classification more difficult, since more intricate structure becomes evident.

Group 1: Small, bright and colourful planetaries

I see these nebulae vividly green and bluish. Good examples are NGC7662 in Andromeda and NGC6543 in Draco. Also NGC7009 (The Saturn nebula) fits quite well although it has the peculiar extensions giving the "Saturn" shape. The "Ghost of Jupiter" (NGC3242)also belongs to this class.

The Eskimo nebula (NGC2392) and NGC1535 in Eridanus form a small subgroup where a fainter outer layer is obvious in addition to the bright central zone.

Group 2: Bipolar planetaries

These are dumbbell or peanut shaped nebulae. M27 and M76 belong to this group. Another fine example is NGC2371/72 in Gemini. The small planetary, NGC7027 in Cygnus also turns out to be biploar, but more assymetrical than the previous ones. The Bug nebula, NGC6302 in Scorpius, could be classified as "peculiar", but could also be considered a member of this group.

Group 3: Annular planetaries.

Many planetaries are annular, but this isn't always easy to see visually. In some cases, however, the annular appearance is obvious at first glance. The best example is M57 in Lyra. But also the Helix nebula, NGC7293 is a good example. I find the small planetary in M46 (NGC2437) in Puppis to be clearly annular, and would finally like to mention Shapley-1 far south in Norma as a good example.

Group 4: Stellar or near-stellar planetaries

These objects are easy to overlook even though many of them can be seen in very small telescopes. At low magnification (in some cases even at higher power) they look like stars. In order to identify them, blinking with an UHC or O-III filter is recommended. Stars will become significantly fainter when the filter is held in front of the eyepiece, while the nebula will remain nearly unchanged.

Good examples are IC2149 (near Beta Aurigae), IC1747 (near Epsilon Cassiopeiae) and IC2003 in Perseus.

Group 5: Large ill-defined planetaries

I haven't observed many such nebulae, simply because they are very difficult to see and require extremely dark and clear skies. They can be impossible to see without an UHC or O-III filter. The Medusa nebula in Gemini (PK205+14.1)is a good example (although its shape suggests that it is "peculiar").

Group 6: Round (or nearly round), colourless planetaries

Maybe the less interesting planetaries to observe visually. NGC2022 in Orion is an example.

Group 7: Floating glass spheres

My favourite group. These nebulae normally have a relatively bright central star. The nebulae themselvs are very delicate, often with bright condensations and dark fields. Sometimes a filter is needed to see the nebula well. NGC1514 in Taurus, NGC1501 in Camelopardalis and NGC246 in Cetus are the best examples. NGC40 in Cepheus and the blinking planetary, NGC6826 in Cygnus should also gives me much of the same impression when observed at higher magnification under good seeing conditions.

I have to admit that some planetaries are difficult to put into any of these classes. Where does the Eight-burst planetary, NGC3132 in Vela belong? And what about NGC1360 in Fornax?

Any suggestions. Other ways to classify the planetaries? Anyhow, I recommend all of you to spend some time observing these nice objects.

Inge S

Easily transportable Dobsonians are very attractive scopes for persons living in areas with light pollution and unstable weather conditions. With my increasing interest for astro tourism, I'm even interested in something that can be transported as checked luggage with the airlines. Presently I'm using a 12.5-inch Portaball which I have brought with me to the Canary Islands on two occasions. In these cases I have brought along the mirror in its cell as hand luggage. The trips has given me many great views, but I have to admit that even the Portaball is a bit large and heavy as air luggage.
In Europe it is possible to get Dobsonians with larger aperture (up to 16") which are considerably lighter than the Portaball and can be collapsed to much smaller volumes for transportation. The trade-off is (probably) less stability and (definitely) a higher price. Optically they are said to be very good even though the thickness of the mirrors are much smaller than the old standard.
My question is: Is ther anything similar presently available on the American market? Is there anyone willing to take the challenge of constructing an ultralight scope in the 15 - 18-inch range? I have seen photos of the new 18-inch Obsession. Definitely a step in the right direction, but still too heavy for me.

Inge S

While the nebuae near and below Orion's belt get a lot of attention, there are a couple of other gas clouds in the constellation which very rarely are observed.
One of them is NGC2174. This emission nebula is associated with a loose cluster of stars, and is situated in the northern part of the constellation. I use Zeta (correction: Eta) Geminorum as a reference point and aim my scope a couple of degrees south and slightly west. The cluster itself is hardly worth the search, while the nebula is large and quite conspicuous even without a filter. The O-III filter enhances the nebula, and some interesting detail can be made out.

Inge S

Spiral structure in galaxies is not easy to detect visually with smaller aperture. However, the spring sky contains a few galaxies where the sprial arms may be made out with moderate aperture when the sky is dark and clear.

For those of you who have clear and dark skies the following project is suggested: Observe the galaxies in the list below and assess the visibility of the spiral features in each case. Use sufficient magnification. Many of the galaxies in the list are quite small, and in my experience the best magnification range for observation of galaxies is 100 - 200x.

Here's the list:

M81
M101
M51
NGC2903 (Leo)
M95
M100
M99
M61
M83 (for those of you who live far enough south)

I hope you'll enjoy these objects.

Inge S

The weather of southern Norway has not given many opportunities to observe the sky this year. Wendesday evening I had my first real observing session this year - then we had some 90 minutes with dark clear sky before new clouds came in.

I checked the seeing with the double star 38 Lyncis. The split was ok, although the components appeared a bit fuzzy at 167x. In cases when 38 Lyncis is not properly resolved, it is hardly worth while spending the time even with deep sky observations.

The first deep sky object of the evening was the globular cluster, NGC2419 - the intergalactic wanderer in Lynx. I haven't observed this object since I got my 12.5-inch, and was surprised by its size and brightness. In fact it is much larger than the distant globular in the other direction, NGC7006 in Delphinus.

Then I went for a galaxy tour in Leo, starting in the west with NGC2903. This is an object that never is a disappointment. It is large and bright and shows evidence of spiral structure. Many Messier galaxies are much fainter than this one.
The next station of the Leo tour was the NGC3190 group just north of Gamma Leonis. These galaxies are very small in size, indicating that they are very distant objects - my guess is 50 - 100 million light years. NGC3190 and 3193 are relatively striking even at low magnification. 3190 is very elongated, while 3193 appears to be round with a high surface brightness.
The two other members of this group are more difficult to spot. 3185 is larger and more diffuse than the two first ones. 3187 is a very faint smudge requiring averted vision with my equipment and observing conditions.

Then I pointed my scope at the fine double, Gamma Leonis and moved less than a degree eastwards to find the striking galaxy pair NGC3226/3227. These galaxies always remind me of an exclamation mark (!) with the elongated galaxy on the top as seen through the eyepiece. A bit closer to Gamma another object was seen, NGC3222. This one is very faint, and it is important to keep Gamma outside the field when observing it.

Moving still further east and slightly south I spent some time with the galaxy group containing M95, M96 and M101 plus several other galaxies. The most interesting of these galaxies is M95. I have always suspected to see some structure in M95, and this was the case even this time. It doesn't really look like a spiral, but more like a letter, theta (a circle with a bar crossing the centre). This time I was careful to notice the orientation of the bar, and checking with a photo afterwards, I could confirm that my observation was correct. M96 appears slightly larger and brighter, but I couldn't see any detail in it.
Galaxy hopping to M105 is easy. M105 is also very bright, but not very interesting visually. It has two companions, NGC3384 and fainter NGC3389, the latter being at least as large as the other two, but appearing more loose-structured and with much lower surface brightness.
North of this triangle there are several other galaxies. I identified NGC3412 and 3377, but there are more objects in this region.

The second last station on the Leo tour was the trio consisting of M65, M66 and NGC3628. These are probably the best of the Leo galaxies. Particularly I like observing the elongated galaxy, 3628 with higher magnification (167x in this case). Then the obscuring dust band along the galaxy's equator becomes visible. At low magnificaiton it appears just as an abrupt drop in brightness at the side facing the Messier galaxies.

Finally I moved north to a rich group of small galaxies dominated by the galaxy pair, NGC3607 and 3608. A fainter object, NGC3599 was seen at some distance from the bright pair. Increasing the magnification revealed a still fainter companion to 3607. This is NGC3605 which indeed could be seen even at 63x magnification, but became much more obvious at 115x. Further east I also found NGC3626 which is appeared very brilliant in spite of a relatively low integrated brightness.

For those of you who want to make the same Leo tour as I did I recommend to add NGC3521. I didn't observe it this evening, but it is in the same league as NGC2903.

However, I didn't stop my observing session at this time, but contained still further east to the two galaxies M98 and M99 in the Coma/Virgo cluster. M98 is an elongated object, and nice as such, but I'm always surprised that it is so faint - one of the more difficult Messier objects. M99 appears round and fuzzy at low magnification, bur by increasing the power and carefully scrutinising it, its beautiful spiral pattern can be made out. It appears as a considerably smaller and fainter edition of M101.

At this point I made a short intermezzo with two fine double stars. Xi Ursae Majoris is a very fine object, and I always recommend other observers to have a look at this historically significant double (actually a quadruple since the two components are spectroscopical doubles). Then I had to look at my favourite, Zeta Cancri. Under very good seeing conditions I can recognise the close pair as a double at 167x. This was not possible this night, and I had to use my 4mm Radian to resolve it. This is the best triple star in the sky for a telescope of my size.

Then I returned to deep-sky observation, turning to another favourite of mine, the Cocoon galaxy which actually is a pair consisting of NGC4485 and 4490. To me it appears more like a pair of goldfish playing with each other. It is a very good object at 115x with the bridge between the galaxies being a challenge to detect.

Next I moved to NGC4618. This is a moderately bright object without any special features. But I noticed something that I haven't seen before. There was another galaxy in the same field, obviously an object in the 11 -12th magnitude range. I can't find this object in Kepple&Sanner, and just wonder if I made a serious navigation error. Can anybody help me with this? Is a companion to NGC4618 mapped or listed anywhere, or is there another pair of galaxies (separated by some 20') somewhere in the region? I continued my tour and found M94 without any problems, so I find this very strange.

After brilliant M94 I turned to M51, and for the first time this evening I was disappointed by the view. I saw two fuzzy cores surrounded by a faint halo, and nothing more. I started wondering if I had strained my eyes too much, but then I realised that clouds were coming in from the ocean. So this was the end of the observations this evening. In practice there are some 3 or 4 weeks left with dark nights here. So maybe it was the last observing session this season.

Inge S

Posting activity has been very low recently. I admit that I didn't contribute too much myself, and the reason for this is that I have a feeling that I already have made posts about everything and want to avoid repeating myself. However, I think it is a good idea to put such thouhgs aside. I encourage everyone to contribute. Observation reports at any level are welcome, and so are any questions relevant to the subject.

As a moderator I will interfere only if I see that a subject probably would get more attention if posted somwhere else or in case of unpolite behaviour.

So, come on guys! I'm sure that you all have something to contribute with.

Inge S

I have to face it. After my last visit to the Canary Islands I had just a few opportunities to observe. It has been raining almost continuously, and if we happened to have a clear night it was often impossible to do deep-sky observation due to moonlihgt. Now the nordic summer season is beginning, meaning that we have to wait until late August for a dark sky.

To keep my astronomy interest alive I need some inspiration. There is one part of the sky containing lots of interesting deep-sky objects which I don't know very well. I'm thinking about the constellation of Ophiuchus, particularly the southern part. I have observed this part of the sky from La Palma, but I missed several of the objects I tried to locate there, and even those I succeeded to find, I could obviously have spent more time with. Can you tell me about your favourite objects (both showpieces and challenges) in Ophiuchus. I know that the region contains many globulars and planetaries, but any deep-sky objects are of interest. The region is also rich in double stars, so why not make a post under the double star forum.

Inge S

For the first time in my lifetime I'm going for the experience of a total solar eclipse.
I'm a bit in doubt about what equipment I should take with me. My only scope is a 12.5-inch Portaball, and even though it is equipped with a solar filter, I just don't think it is the right instrument to bring along on the long trip.
I'm considering to buy a pair of binoculars and/or a small refractor. It is hard to find refractors with equipment for solar projection today, but it should be possible to improvise something.
Or maybe I should just skip equipment and enjoy the moment with the naked eye.
Any suggestions?
Is there anyone who plan to go to Novosibirsk for this event?

Inge S

The brightest stars of globular clusters are normally orange giants. The HR-diagram of an old cluster shows that all the massive stars have moved away from the main sequence to the giant stage (Many good examples are shown in Burnham's celestial handbook).

A few years ago I realised that I could see the orange colour of the brightest stars of some globular clusters. It started with the relatively coarse (and relatively close to the solar system) cluster, M4. I observed this object for the first time from La Palma, and immediately noticed an orange double standing out from the cluster population (I doubt that this is a binary star. Probably just two bright stars at nearly the same line of sight). Later, when observing M22, I was struck by some 20 or 30 bright stars of the cluster, all orange. Somehow these stars appeared to float in front of the cluster. This is an illusion, of course, but very beautiful, since the "background" star cloud appeared whitish. Last weekend I observed the same in M13, but not in M15 and M92.

Have anybody else noticed this? I use 12.5 inches of aperture, but I guess that a keen-sighted observer can do with less. And with big scopes I would expect colour to be even more easy to detect.

Inge S