Starwiz

14 minutes ago, ShaunyC said:

Hi John, thanks for your comment, 

Everyone has to start somewhere I suppose, hopping out my window will just give me an easy opportunity to get acustom to using the scope and set up, then abit of experiance with stacking and post processing... So I asuppose this is all more of a training exercise than anything.. 

Once I've got my head around everything and improved certain bits of my equipment I can easily imagine myself going on adventures.. 

My house is in approx bortle 6 and i can see a few stars on clear nights to the left as there's a school playing field.. 

But when I do decide to venture out I'm 10-15 mins from bortle 4 which is also on the coast.. I have a few spots in mind already where I go star gazing usually when there's a meteor show on.. Shame I'm working nights this weekend but at present can't imagine the skies to be clear anyway..... Again... 

I also go sea fishing quite abit.. So I'm sure I will be intertwining the two hobbies before long

And for this reason I'm swaying back to a 130pds, but it's just a case of which scope turns up 1st I think

The 130pds sounds like a good choice.

For a Bortle 6, a light pollution filter will help a lot, especially if it's sodium lighting.  I bought the Astronomik CLS, the version that clicks into the DSLR above the mirror.  I could hardly believe the difference it made imaging the Horsehead which was located about only 10 degrees above a sodium street light from my back garden.

Most people start their journey into astro-photography by imaging the planets as it's easier and less expensive than the kit needed for DSOs.  To do this, you need to shoot a couple of thousand frames video and then use a stacking program to select and stack the best frames.

The sea fishing sounds good, I do that myself sometimes.  I'd keep the telescope optics away from the sea air, although you may be OK if the breeze is a leeward one. 

John

My first views of Mercury and Mars were through an open window. 

Yes, although it won't be ideal for the reason others have mentioned, you can still have a lot of fun and if it's very cold outside you will be warmer in the room.

But at some point, you may want to take your kit outside or to another location, so bear this in mind when choosing what you buy.  Also consider what light pollution you have to contend with and what other buildings are nearby that will produce rising heat degrading your views further.

John

An alternative to Stellarium is 'Cartes du Ciel'.  Both are free bits of software and do pretty much the same job, so it's a matter of preference.

https://www.ap-i.net/skychart/en/start

If you 'right-click' on an object, then click 'About', it will give you all the information including the coordinates.

John

Hi Lee,

There will be better qualified people on here to answer number 1.

Number 2 - I don't bother with books these days as there is a huge amount of information on line.  A good place to start would be with the Messier objects.  Pictures and coordinates are included in this page for instance.

https://en.wikipedia.org/wiki/Messier_object#:~:text=The Messier objects are a,Nebulae and Star Clusters").

John

On 21/11/2020 at 15:22, Stu Wilson said:

ive got a very similar setup.

Skywatcher  200P, NEQ6pro, Orion Starshoot  Autoguider, QHY8L main imaging camera, Rowan Belt Mods.

Just added Altair Quad Band filter and Skywatcher Coma corrector into the train, with correct spacing ive achieved the result that I think your aiming for.

Thanks.  Yes, the stars in your image look much better than in mine.

John

1 hour ago, Nikolas74 said:

Is it necessary to do a 3 star alignment before running plate solve ? or just a polar align will do ?

As others have said, no star alignment necessary, just polar align.  Plate solving is doing all the alignment for you.

Coma corrector is on it's way but I can't get my hands on it until 25th December.  🙂

I'm hoping it's the step I need to get rid of some horrible star shapes that plague my images, hence I've lost the motivation to do any more imaging until I get it.

John

Another fan of Plate Solving.  It's saved me many hours since I took the step just over a year ago.

John

8 hours ago, MarkAR said:

Very good close view and nicely framed. Little bit saturated for my taste and some magenta showing quite strongly in the stars. Overall though you've got some superb detail, well done.

Thanks.

It's the first time I've tried placing stars over the top of the SHO stars without removing them first, so I can probably improve on this.  I was previously using Straton to remove the stars, but it seems to mess up the nebula quite a bit and makes it look really noisy when I zoom in.  The saturation level looks different on different screens, something I've noticed before.  It looks over-saturated on one of my laptops but not on the other, and different again on my phone.

John

NGC 281, also known as the Pacman Nebula, although I can't imagine Edward Emerson Barnard calling it that when he discovered it in 1883. 

Imaged from Malta during the last couple of weeks.

John

Very nice!

Shorts, T-shirt, chair, table and a cold beer at this time of year in Malta.

The mozzies are big and going to bite me anyway but I'm gradually becoming immune.  🤣

27 minutes ago, alacant said:

Were you on stable ground and at both the meridian -az-  and at 90° -alt- to it?

I find pHd2's traditional drift reliable although the eq6 altitude adjustment leaves a lot to be desired; I always need to finish with the south bolt clockwise and take up any slack with the north bolt, otherwise it moves.

HTH

Yes, on my terrace that has stone tiles.  I also put some of my diving weights onto the mount's eyepiece holder to make it even heavier.

I've given up trying to adjust it by the bolts, so I just alter the height of the back leg of the tripod.

I'm probably just not very good at drift alignment yet.  😀

John

17 hours ago, alacant said:

Hi.

That's more than acceptable. In fact you may want to increase the error so that DEC guides in one direction only. Guiding apps will happily cope with a large pa error. I keep my eq6 around 3' to 5'. 

Cheers

17 hours ago, Realtimedoctor said:

Polar alignment accuracy and what is a good number is very debatable. Some people deliberately keep it around 5 arc and guide Dec in one direction as @alacant described.

Some like me, like to get it as low as possible. My usual PA error is ~2arc min, if I'm very fussy, and have time then try to get it as close as physically possible. You can't get a zero error (due to multiple factors beyond your control). 

In practice as long as your PA is less than 5arc min, you should be able to guide that out. Though, with an off axis guider you should have good balance, especially as you are guiding at 1000mm FL. 

You can also try and guide the Dec only in one direction irrespective of the PA error, depending on which direction your mount guides smoothly. 

I've an EQ5, way smaller mount that yours and also guide a 200p with a Finder guider. I can easily manage to guide at ~1 - 1.2 arc sec RMS (some would say its not good enough, for me works perfectly fine) 

Don't pay much attention to the numbers, see what your subs look like. That should be your benchmark, rather than an arbitrary number to aim for. 

 

Good luck. 

15 hours ago, alacant said:

Couldn't agree more. The numbers mean nothing if you're satisfied with your final images;)

Cheers

Thanks.  I tried a drift align last night and this morning the PHD2 log said it was 7.5', so a lot worse.  🤣

48 minutes ago, MarkAR said:

If the log says 1 arc minute then there's room for improvement. I use Ekos rather than PHD2 and easily get less tham 12 arc seconds. Thats under 12".

The better your PA the better your guiding will be and that's the important factor. With good PA on a NEQ6 you should be able to get under 1.0" RMS guiding.

Thanks, I may try a drift alignment tonight to see what I get.

John

Does anyone know how to determine the level of PA accuracy needed?

I'm taking narrow-band subs of 6 minutes using a SW200P on NEQ6 and guiding using OAG.

My last PHD2 guide log says PA is 1.0', but I don't know if this is good enough or not.  It would be good to calculate maximum permissible error based on my set-up.

Thanks

John

2 hours ago, alacant said:

Not so damp here until later on in the year, but here's an example with HFD.

Same telescope and guide calibration on consecutive nights. One with easterlies, 3.0, The next, northerlies, 2.6. Same part of the sky:

Thanks, that's interesting.

John

24 minutes ago, alacant said:

That's great news.

I think we're at about the same latitude. What i find at this time of year in particular is that the seeing -and so the guiding- is dictated very much by the air stream. The coastal strip here north of Alicante is only about 10km wide with steep slopes immediately to our west. Anything with an easterly component throws up haze as the damp air rises and cools. Everything else is dry and so the seeing remains constant all night. I wonder if you may be similarly affected? Maybe worth investigating, particularly as you become more automated. I think guiding is very much affected by seeing.

Cheers 

Thanks, that's interesting.  I'm about 3 degrees further south, but it's worth investigating.  Being surrounded by sea, it can get very humid in Malta and I always put a towel over my laptop at night, sometimes finding it quite damp by the morning.  I could also probably do with a better guide camera as the ASI120mc isn't the best choice, especially with OAG.  I originally bought it for planetary use before I even considered imaging DSOs.

John

On 10/08/2020 at 17:56, michael8554 said:

I've looked at the Star Lost positions in the Log and to be honest I don't know what is really happening.
So I will theorise 😆

First you haven't made any Dark or Defect maps for the camera, so the chances of locking on a hot pixel are high.

 

 

PHD2 then continously send Max Dur corrections (up to the horizontal red dotted line), trying to move that pixel into the centre of the guide box, which it never will be able to do.

(Note the vertical scale is 50arcsecs, so the normal guide pulses leading up to the Star Lost are too small to see, and I've only shown Dec for simplicity).

I notice that all the way through your guiding, PHD2 is showing the SAT message on every guide exposure - PHD2 auto select shouldn't select a Saturated star ?

Even on the very low star signal (yellow line), SAT was indicated.

Was the red SAT message not showing on the bottom taskbar?

You might try changing your Star Detection method.

 

Your guide HFD is about 3.5 pixels, so you could deselect Star Mass Detection and set HFD to 2, which is a higher figure than a hot pixel.

Though the PHD2 developers deny it, I believe it is all too easy to widely loose position during a Star Lost situation.

Finally, I think you're very brave leaving your mount unattended for long periods, when the chances of mount Runaway or uncorrected Star Loss are not zero, leading to wrapped cables or tripod/counterweight intimacy .

(and lots of wasted exposures).

Michael

I'm pleased to report I've now had three straight nights of full imaging since I implemented the above changes although it's been completely free of clouds each night.

The last two nights, I've selected the star manually as it always seems to auto-select the brightest star which results in the star being saturated .  Is there a way to change the settings to improve auto-select of the star?

Thanks

John

Imaged from Malta during the last couple of nights.

John

59 minutes ago, michael8554 said:

I've looked at the Star Lost positions in the Log and to be honest I don't know what is really happening.
So I will theorise 😆

First you haven't made any Dark or Defect maps for the camera, so the chances of locking on a hot pixel are high.

 

 

PHD2 then continously send Max Dur corrections (up to the horizontal red dotted line), trying to move that pixel into the centre of the guide box, which it never will be able to do.

(Note the vertical scale is 50arcsecs, so the normal guide pulses leading up to the Star Lost are too small to see, and I've only shown Dec for simplicity).

I notice that all the way through your guiding, PHD2 is showing the SAT message on every guide exposure - PHD2 auto select shouldn't select a Saturated star ?

Even on the very low star signal (yellow line), SAT was indicated.

Was the red SAT message not showing on the bottom taskbar?

You might try changing your Star Detection method.

 

Your guide HFD is about 3.5 pixels, so you could deselect Star Mass Detection and set HFD to 2, which is a higher figure than a hot pixel.

Though the PHD2 developers deny it, I believe it is all too easy to widely loose position during a Star Lost situation.

Finally, I think you're very brave leaving your mount unattended for long periods, when the chances of mount Runaway or uncorrected Star Loss are not zero, leading to wrapped cables or tripod/counterweight intimacy .

(and lots of wasted exposures).

Michael

Many thanks.  Lots to think about and try in there.

John

41 minutes ago, DaveS said:

Ooh, I do like this. Some lovely colours and the central pillars are hanging there like an abstract jewel.

Thanks. 

14+ hours of Ha data in this one.  I also used the Ha as the luminance layer, so wanted to get the best definition I could.

John

Imaged from Malta over several nights.

John

1 hour ago, whipdry said:

I had a similar issue with PHD2 the last couple of nights, decided it could be the high temperatures effecting my uncooled guide camera... making a new set of darkframe at 24° C seems to have fixed it.

Here's what the issue looked like on screen;

 

Peter

Thanks, I'll give that a try.  I also have an un-cooled guide camera and it's in the mid-20s at night in Malta this time of year.

I had a full imaging run last night for the first time in several days.

John

9 hours ago, michael8554 said:

Can you identify what time that frame was taken and post the relevant PHD2 Guidelog  ?

Michael

The file time for that frame was 08/08/2020 02:40:41.

Files attached.

Thanks

John

PHD2_DebugLog_2020-08-07_213456.txt PHD2_GuideLog_2020-08-07_213456.txt