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Pleiades gone wrong.

Highflight

By Highflight
in The Astro Lounge

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Highflight

Highflight

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Is it me or have the Pleiades lost their nebulosity? It's a crisp clear night tonight, so decided to give the big bins an airing and took a look at my fav cluster. I thought I'd got the wrong set of stars to start with, but after carefully locating them, I studied hard but they just don't seem right. All of the nebulosity has dissapeared and just seeing ordinary stars. Anyone know why?

Chris. :icon_eek:

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Talitha

Talitha

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Maybe the transparency's below average? Check the objectives, too.. if it's damp out they might have some slight fogging on them. Or maybe the eyepieces are fogged up.. when it's cold, this could happen from 'breathclouds' or from your eyes' moisture. :icon_eek:

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661-pete

661-pete

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I think you cannot see the nebulosity with binoculars, I'm afraid - nor even with a fairly large telescope, visually, unless observing conditions are really excellent. If the sky is anything other than utterly dark you won't see anything. It is extremely faint compared to the background sky, and usually needs photography to bring it out. But enjoy the cluster for what it is, visually, a brilliant assemblage of glittering stars! You will see how many more stars the bins reveal, than the naked eye.

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Highflight

Highflight

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Thanks Carol.

I checked for dew/mist, but seems ok. I just dragged the lx90 out to double check, and same thing. The lx90 has dew heaters, so no mist on the lens or ep. Seems strange. I've never seen Pleiades without their coat on. lol.

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Talitha

Talitha

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You cannot see the nebulosity with binoculars, I'm afraid - nor even with a fairly large telescope, visually. It is extremely faint compared to the background sky, and needs photography to bring it out.

With all due respect Pete, you can see the nebulosity visually. :icon_eek:

Link: Nebulosity in The Pleiades

The transparency here was above average last night, and i saw the glow while making a sketch with the 120ST. No fibrous structure was seen, but the background glow was definitely there. :)

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calibos

calibos

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I was going to talk about dew on the lenses alright, but not in terms of its presence causing the nebulosity to disappear but in terms of its absence causing the 'nebulosity' to disappear.

I've never seen the nebulosity myself so I took it as gospel what others said about it only being visible in astrophoto's. Apparently I was wrong. I'd kill for your skies if you get to see it so much that it being absent made you sit up and take notice.

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661-pete

661-pete

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With all due respect Pete, you can see the nebulosity visually. :)
You may note that I edited my post slightly from the version you quoted, after doing a bit of background checking (not quite literally! :icon_eek:). All I can say is, this comes as a surprise to me, I have certainly never seen it myself but then I don't suppose my eyes are up to it! ;) Did the pre-photography cataloguers like Messier and Herschel mention the nebula, by any chance?
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Highflight

Highflight

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I had the same thing tonight. Was using my 300P with a 32mm EP and saw no nebulosity at all.

I found it where I am tonight to be very damp and I had dew problems fairly quickly.

Sly, How are you getting on with your new scope? Hope it's giving you plenty of good views.

Chris. :icon_eek:

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Highflight

Highflight

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I'd kill for your skies if you get to see it so much that it being absent made you sit up and take notice.

Calibos, I view the skies from a place called Stoney Cross Airfield, which is situated in the New Forest National Park near Ringwood, Hampshire. The view of the night sky from here on a clear night is absolutely breathtaking. I'm not exagerating when I say It's as black as black can be, and the stars are from horizon to horizon, 380*, lp is almost zero. If ever your over this way, try it. You will be amazed at what you can see on a clear night, even with the naked eye, and yes, Pleiades nebulosity is just visible with the naked eye from here.

All the best and clear skies.

Chris.

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Highflight

Highflight

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Chris,

Thanks for the tip: I'm only about 30 minutes from Stoney Cross so will definitely give it a try. I just had a quick look on Google maps - can you please tell me what's the best way to access the site? It's not very obvious from the overview I saw.

Depends on which direction your coming from. From Ringwood it's easy. Go up the long hill (A31) and go past the two petrol stations, ( Picket Post) and after about a mile or so, turn left and follow to Stoney Cross Airfield. But coming from Southampton/Cadnam direction, oh hell!. You need to go to Cadnam rbt (under motorway) and take the road to Brook. At Brook you will come to two pubs, Green Dragon and The Bell. The road divides, take the left hand road and follow to Fritham. Turn left (signed Ocknell camping site) follow road for about 1 1/2 miles (don't go into Fritham village, stay on main road). Stoney Cross will come up on your right hand side. (or, you could carry on to Ringwood, do a u turn and come back up to Picket Post). I usually go into the first car park and then set up in the bushes.

Hope this helps.

Chris.

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Highflight

Highflight

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Chris - thanks for that: I see where you mean now. Am very excited to have found a new dark site- perhaps I'll see you there sometime (or not, if it's as dark as you promised!)

Mind the cattle!!! you can't see them coming and it's really spooky out there. lol. It really is BLACK. Have a great time.

Chris.

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Highflight

Highflight

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Nice view. So is the car park you meant the first roundish one to the left of the right-hand road, or the long one on the right of the road? I'm guessing the long car park on the right is too close to the road proper, and you'd be distrubed by headlights.

Neither. About halfway up the picture are two white patches on the right, just where the perimiter bends to the right. These are the main car parks and I usually park in the 'top' one and then walk out to the runways and set up on the 'X' where the runways cross. Keep your eyes open for them ruddy Merlin ghost's, they're not fussy who they land on, lol. :icon_eek:

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simon84

simon84

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Hi Chris,

Had a good time with it last night, got some nice views. Started off with Jupiter which looked great, plenty of detail. Then just started playing with it, slowly scanning the skies just having a look. Managed to see the Pleiades also which looked great. After that I waited for Orion to come up and then spent some time looking at that, at which poing my secondary was starting to get rather wet so called it a night. Spent this morning looking at some dew control measures so as first light goes I had a good time.

Cheers,

Simon.

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Highflight

Highflight

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Hi Chris,

Had a good time with it last night, got some nice views. Started off with Jupiter which looked great, plenty of detail. Then just started playing with it, slowly scanning the skies just having a look. Managed to see the Pleiades also which looked great. After that I waited for Orion to come up and then spent some time looking at that, at which poing my secondary was starting to get rather wet so called it a night. Spent this morning looking at some dew control measures so as first light goes I had a good time.

Cheers,

Simon.

Really pleased Simon, well done. I found the best dew heaters to be Kendricks, but they are pricey. I've got objective and eyepiece heaters on my LX90 and they work a treat. Be carefull not to overdo it, otherwise you'll get heat haze inside your scope. Just remember, if it's not glass, it doesn't need heating, unless you've got a metal reflector, of course. lol.

Chris. :icon_eek:

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jah79

jah79

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Just remember, if it's not glass, it doesn't need heating, unless you've got a metal reflector, of course. lol.

Chris. :rolleyes:

I'm a noob with a metal reflector and after my first night out in the freezing winter recently I wondered about all sorts of stuff relating to dew, hot/cold, frost etc. What difference would heating make to my viewing/scope?

Also after 4 hours outside I brought the scope in to the warm house. I left all the caps off (including off the EPs). Wiped moisture off scope and mount, put pillowcase over open holes of scope and then replaced all caps the next morning. Is this the correct way of going about things? I read on a nother forum that you should replace all caps before going into a warm house and that this is very important to stop condensation in the tube, was a bit worried after reading that coz obviously I did it the other way round (which I read on SGL somewhere I think).

Thanks

Johann

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661-pete

661-pete

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Don't know how much help this is, but on my Newtonian I have noticed that the Primary (and, I think, the secondary too) never get dewed up during actual observing or imaging. What does get misted up is the finder scope and the EP (if I'm using it). For the finder I just play a hairdryer over it from time to time.

The body of the 'scope gets very wet with dew during sessions, but not the mirrors. Like most mirrors, they are glass.

I don't know why this is: is it due to moisture-laden air not being able to get to the bottom of the OTA or something? And that doesn't explain the secondary...

Anyway, when bringing in the 'scope on a cold night, I find that then is when the mirrors misting-up can start. So, now, I don't take it into a warm room, instead into one of the spare bedrooms which is unheated and fairly chilly. I leave the tube cap off until the next morning. And that seems to stop the misting up.

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