Monday, August 17, 2009

Found Pease 1! And tested some nice eyepieces (16 August 2009)

Again a nice & clear sky, the 3rd in a row. I don’t need to work tomorrow so no worrying about staying late.

I have tonight also the opportunity to test some eyepieces (thanks to Hubert). I have an Astrolan ultrawide 30mm (80°) which provides me with a FOV of 1,2°, as well as a 9mm Nagler T6 and 4.8mm Nagler (the discontinued version) 

It’s not totally dark when I’m starting to test them. But that’s ok as I’m doing some side by side comparison. 

1. The first object was M13:

Astrolan 30mm (68x) vs. Pan 24mm (84x)
- A great FOV with this Astrolan (1,2°), much larger than the Pan (46’). But of course at the expense of a smaller magnification
- I have astigmatism with the Pan, but even more with the Astrolan. However, it disappears completely when I’m putting my glasses on.
- A bit of (vignetting). Don’t know how to translate in English 
- Good eyepiece for starhopping (see later in this report)

9mm Nagler vs. 9mm Celestron Plossl (225x)
- Nagler is providing sharper stars than the Plossl
- But the Plossl  goes slightly fainter!
- The FOV of 35' is just great

9mm Nagler vs. 9mm Celestron Plossl combined with Powermate 2,5 (563x)
The Nagler provides again sharper stars, but also here the Plossl goes fainter.

4,8mm Nagler (422x) (not compared with another eyepiece)
Sharp images, even at this power! Comfortable FOV of 20'. This is a great eyepiece!

Note 1: while testing I did not know this was a discontinued version and that the 5mm Nagler T5 provided a twice as large FOV. In fact, it's good I did not know, because it provides an unbiased opinion on this 4.8mm eyepiece. 

Note 2: I found on Cloudy Nights quite some remarks on the short eye relieve of this eyepiece. I don't recall having been confronted with this issue during my testing. It's true however it's impossible to observe through this eyepiece with glasses.

4,8mm Nagler with Powermate 2,5x (1055x)
Stars are small discs.

2. Next test was to find Pease 1 in M15
I have found Pease 1 (with Blinking Technique!) with the following eyepieces:

Celestron 9mm + Powermate 2,5x: blinking worked well because I do not have reflections on the filter as I can bring it real close to the eyepiece.

Nagler 9mm + Powermate 2,5: blinking more difficult as with this eyepiece I cannot bring the filter close to its edge, due to the firm eyecaps. I have reflections on the filter which makes it difficult to blink. I had only success when putting a dark cloth over my head.

Nagler 4,8mm: “easy” (everything is relative, so I mean in fact easier than with the 9mm and Powermate) 

3. Ringnebula (M57):
Nice image at 422x (4,8mm Nagler). Still able to observe it at 1055x but it becomes more difficult due to inaccurate tracking. Stars are little discs. Could see a star of mag 15.6 close to the edge (not visible at 422x) and maybe the central star. 

4. Little Dumbell (M76)
Here the 9mm Nagler gives a better view than the 9mm Celestron Plossl. I can see a bit more details on the nebula, and this time I see also a fainter star, which is not viewed with the Plossl. The 9mm Nagler (225x) gives a better view than the 16mm with Powermate (316x). 

5. Starhopping with Telrad and Astrolan 30mm 82°
I’m not used to starhop, so I admit I’m not good at it. However, I also know it’s always a little moment of joy when you found a DSO by your own means. I decided to give it a try by using the Telrad and the Astrolan with it’s 1,2° FOV. Without finder it’s of course a bit harder, reason why I limit myself to the obvious Messiers.  

I did not use starhop charts or an Atlas, only the constellation charts in the “Nigh sky observers guide” have been used. 

I have been able to find M13 (that’s really not difficult), M92, M56, M57, M29, and M15. I had to cheat a bit with M92 and M15: I did not found it immediately, so I used the ArgoNavis to locate, and then looked at the Telrad to find its position (aha, it's there!). Then I tried again only with the Telrad, and it worked. I repeated it a few times to save it well in my memory. I intend to try it during my next observation session.

So here is my eyepiece conclusion: 
- Astrolan 30mm (82°): fine eyepiece if you don' suffer from astigmatism. Otherwise it's OK when wearing glasses (which is not always possible when there is a lot of humidity in the air). It’s also a great eyepiece to starhop. 
- the cheap Celestron 9mm eyepiece is not bad compared to the Nagler 9mm. The Nagler is a bit sharper and provide some more details on a nebula. But the real “plus” of the Nagler is the field of view of 35'. Replacing the Celestron Plossl just for the quality of the image is maybe not worthwhile, unless you’re aim is to get the larger FOV or when you are obsessed by pinpoint stars.
- The 4,8mm Nagler is a great eyepiece. Unfortunately I have not been able to benchmark it with another one so I cannot judge if the premium price is justified. But I can imagine that at that power a larger FOV of 20' is real advantage and worthwhile over a traditional eyepiece. As stated previously I did not had an issue with the short eye relieve. If I have the opportunity I should compare this 4.8mm Nagler with the still active 5mm Nagler T5.  But honnestly, not knowing this 4.8mm was an discontinued version I was pleased with the view it gave me.

Great evening, and I can add Pease 1 to my observation list!

Addendum: observed the folllowing night once more with the 4.8mm Nagler, and indeed, it's a short eyerelief. Not really an issue when there is no condensation, which is  quite rare in our regions.

Sunday, August 16, 2009

Perseids (Aug 11, 2009)

One night before its peak I’ve observed the Perseids with my 14 year old son. We are lying on the long chairs in the garden, looking towards east and north and hoping to catch those falling stars.

This is some real quality time to spend with the kids. It’s a ritual I try to do with my kids since some years, with relative success, either due to the weather, either due to the willingness of the kids to participate.  

Tonight we talk a little bit about the stars, I look if he still recognises the constellations (he remembers the summer triangle), we see some satellites (and planes too) and of course we are all excited when we see a meteor. We haven’t seen a lot of Perseids tonight. During the half hour we watched (from 21:00UT to 21:30UT) I’ve seen 6 and my son 5. I’ve seen a bright long one with glowing light and sparkles of light. 

The next night with the maximum is completely clouded. 

A very rare event: Jupiter occults a bright star (45 Cap)

Tonight there is a very rare astronomical event on the menu. Jupiter occults 45 Cap, a star of mag 6.0. 

The Electronic Bulletin van de BAA is giving the following info: 
Jupiter will occult the bright star 45 Cap (HIP 107302) on the night of 2009 August 03/04 (Mon/Tues). The star is visual magnitude 6.0 and, for European observers, will be the brightest star to be occulted by Jupiter for the next 100 years.

And yes, we are lucky, the sky is clear so no doubt we will see this event. Unfortunately the seeing is terrible, one of the worst I’ve ever seen, which has been reported too by other Belgian observers. The 4 main moons of Jupiter were all visible as well as 45 Cap, which is the closest to Jupiter. I started observing at 22Hr15UT which is around 40 minutes before the occultation. At around 22:50UT the tension is increasing, the star is getting real close to Jupiter. Then suddenly it’s gone and in the next 30 seconds I had the impression it pupped up a few times (difficult to say due to the seeing): a fist one (quite sure), a 2nd one (not sure) and a 3rd one (sure). 2 flashes have been reported by other observers too. The star reappeared 2 hours later but I have not observed this.

Rendez-vous is made again in 100 years!

A frist try to Pease 1

More than 1 month I have not been observing. During July there were a couple of good nights, but could not find enough motivation to get the scope out. This year has been very tough (I’m working in automotive). But after a good week of holiday I’m ready to watch the stars again!

The sky conditions of tonight are not very good. There are high clouds and it’s not very transparent. NELM is around 5.0. I have no descriptions of what I observed, except of the search to Pease 1 (planetary in M15) and Jupiter.

Pease 1: Pease 1 is a little planetary nebula in M15. You need a good finder chart to catch this object. Luckily there is a good website where you find all the required or

It’s a 3-step approach to find it. First you need to find the 4 trapezium star, which is not difficult at 311x. Step 2 is to locate a triangle east of this trapezium and continue you path to a faint stars towards the north of the globular. The triangle is still easy, but finding this faint star becomes more challenging, but still doable. For step 3 you need to pump the power to 500x: we need to go from this star a small 28” to the nebula. Not easy because there are a lot of stars and due to the high power they are all like little discs. I could see “something”, a disc maybe somewhat larger than the stars but I’m not too sure it’s the planetary. When looking at observations from other people I conclude this is not yet Pease 1. But at least, I’m more prepared for the next try as I’ve walking around in the region …

Jupiter: I’ve never seen Jupiter as well as during this evening: amazing lot’s of details in the belts with all kind of structures, color differences etc. Besides the 2 main belts I could see some other ones. The red spot was also visible, but unfortunately the impact was still “behind” the planet.