Lucas Barclay

Here is my first attempt at imaging the Hubble variable nebula! Unfortunately I only have two frames spaced out a month between each other but there appears to be some activity present still! I took this image from London which was shown to be a challenge with the light pollution (as well as the full moon in the second frame). The first frame was taken on 21/02/22 and the second was taken on 19/03/22. I'm, hoping to continue this project and take frames at more regular intervals too. The equipment I used were : 

-ASI178mm

-Nexstar 5SE alt-az mount

-William optics ZN73

I took this animation of a sunspot in region 2936 over the course of 4 days! Unfortunately the conditions during some days were not optimal but I think its interesting to see how it develops over time! I took 4 separate videos of the sunspot each on different days and then stacked the frames of those videos separately. Once I did this I layered them on top of each other to create this gif. The first frame was taken on the 30th January. Equipment : 

- ASI178mm astrophotography camera

- Nexstar 5SE

- Baader ASSF solar filter 

7 hours ago, robin_astro said:

The uploaded tiff image seems to be 1.5x larger than the camera sensor (4644x3120 compared with  3096x2080)  has it been resampled somehow?

Cheers

Robin

Just went out tonight and decided to try do the spectra of one of the stars in Pleiades! I think it has actually turned out pretty well I just wanted to confirm and see your thoughts on how the graph looks!

26 minutes ago, robin_astro said:

The uploaded tiff image seems to be 1.5x larger than the camera sensor (4644x3120 compared with  3096x2080)  has it been resampled somehow?

Cheers

Robin

Ah yes, I took multiple images of the spectra and then stacked them up to try and get a bit more detail through!

18 minutes ago, robin_astro said:

OK I think I know what has happened. It looks like you have captured the second order (the next spectrum out) This will be ~2x longer and much weaker than the first order, particularly in the blue. I think You will be surprised by the much shorter exposure you will need when you find the right spectrum !

Cheers

Robin

Ahh I see! I will try to get the correct one next time! I am wondering now though, could I have gotten the two ends mixed up? By mirroring the image it somewhat looks more correct than the original.. 

1 minute ago, robin_astro said:

OK it looks like you should just be able to fit the zero order and spectrum in the frame. Check the grating is rotated so the brighter blazed spectrum is to the right of the zero order (There is a mark on the Star Analyser filter cell to show  approximately the correct orientation) and place the zero order near the left edge of the frame. To get you started, the blamer lines should then be roughly in the right place. For example H beta at 4861A should be ~4861/2.7 = 1800 pixels along from the zero order. 

It still does not explain the apparent low sensitivity in the blue (Do you have any other filters in the imaging train?) but we can worry about that once we have the full spectrum and zero order in the image

Cheers

Robin

Got it! I do have a few other images I took with my DSLR camera but I have yet to look at them in much detail yet, though with my DSLR I believe the entire spectra should be present including the zero order so I may have a look at that too!

3 minutes ago, robin_astro said:

Can you post a screen shot of the calculator with details of your current setup entered please

Robin

Of course! Thank you for all these links I shall have a read through them now! Here is what the results come out as on the calculator :

I took 60 20 second exposures in red, green and blue totaling to 180 20 second exposures. Here is a list of the equipment I used!

Camera - ASI178mm

Telescope - William optics ZN73

Mount - Nexstar 5SE alt-az mount

Filters - RGB

Processed in astro pixel processor!

Recently I took this image of the Orion nebula and I'm pretty happy with how it turned out! The image is false coloured since I use a monochrome camera (ASI178mm) but I think it still looks pretty good! I'd be happy to hear your opinions and any improvements you would recommend!

9 hours ago, robin_astro said:

This is more like what I would expect to see (in black)  Are you using a mono or colour camera ?

Thank you for all the help so far! I may need a bit of help on producing that calibrated spectrum since I am not quite sure how to do that.. I used a monochrome camera for this spectra (ASI178mm) with my william optics ZN73 and the staranalyser 200 which was about 45mm away from the sensor. I'm not too sure what you mean about the brightest of the two spectra nearest to the zero order though.. Sorry for not knowing much about the process of spectrometry, I have only recently begun! Here is an image of the spectra produced without taking a cut from it : 

21_16_45_lapl5_ap4930_Drizzle15.tif

Good evening!

I recently got my hands on a star analyzer 200 and took a glance at Sirius. As a result I was able to gather this spectra from the star. Although I am struggling to annotate it and make some observations of the star. I also feel as though some of the absorption lines are due to atmospheric interference. Any advice or tips would be appreciated! The software I'm using is Visual spec for reference!

On 11/02/2022 at 22:10, Ed astro said:

I am not sure whether the dimensions of the waveguide are right but even though the antenna may not be ideal it is still definitely worth trying to detect the hydrogen line! See for example this project where HI was detected with an antenna made from a paint can: http://parac.eu/projectmk9.htm

The probe length of 5 cm should be OK, maybe it is a few mm too long (in my can feed it is 4.6 cm) but the few mm difference probably does not degrade the performance too much. Probe placement with respect to the back of the waveguide is quite critical but should be about 8 cm. Another thing that can really help is mounting the LNA as close as possible to the probe in order to minimize cable losses. 

Have you already tried to observe outside with the Milky Way overhead? Inside you will probably only receive the thermal emission of the ceiling… 

The frequency of HI is 1420.405752 MHz plus or minus about 1 MHz due to Doppler shift, but usually the strongest peak is close to the rest frequency.

Best regards,
Eduard

 

By the looks of things I'm still not receiving anything on the hydrogen line.. Is there a possible rig you would recommend for doing radio astronomy? I can't seem to find any antenna or satellite dishes that are suited for the hydrogen line.. Could I have done something wrong with the wiring too?

2 hours ago, SteveBz said:

Hi Lucas,

How did you set up the radio? I'm just waiting for parts at the moment and I'd love to see how other people are doing it.

Steve.

Oh! Well this is actually the second time I've tried making a cone antenna and this is the largest I've made so far.. I mostly used a bunch of amazon boxes to construct it and after realizing I didn't have much, I decided to create a mesh instead for the foil to wrap around. Of course this sacrifices durability and structure but hopefully it should still work! With the probe I didn't have a special adapter so I have made sure to keep the outer mesh in contact with the foil on the inside and the copper core probe separate. At the moment I am trying to get it to work on my windows computer but once I see a sign of the hydrogen line I'm planning to try and automate it on the raspberry pi and build a map of the milky way (I may also turn it into a community project on my website if possible). I haven't attempted putting it outside yet but I'm planning to tomorrow hoping that it doesn't decide to rain (or rip apart my antenna..). I will give an update once I attempt this!

1 hour ago, Ed astro said:

Hi Lucas,

the narrow spikes are all RFI, although I can not tell you where it comes from (maybe a switching power supply or a computer near the antenna?) 

the hydrogen line signal is quite weak- usually no more than 0.5 to 2 dB above the noise floor. You can change the vertical scale in the IF average plot with the “gain” and “level” sliders to make the weak signals more easily visible, or you can export the spectrum as a .txt file and plot it in excel. 

If you already tried that and still see nothing then there is probably some technical issue…

By the way, could you give us a short description of the setup you are using?

Best regards,

Eduard

Ahh interference could be it since I have only been testing my setup in my room nearby to my computer and other devices.. Is there a specific frequency for the hydrogen line to focus on by any chance? My setup definitely isn't the best as I've tried to work with cardboard and tin foil. I made a horn antenna as seen below, it definitely isn't the best construction but I thought I may be able to see some results from it. The waveguide is 15cm by 15cm and the copper core is roughly 5cm in length. I think I have a complete circuit by keeping the outer copper mesh in contact with the foil lined on the inside but I may be wrong.. I use a generic nooelec rtl-sdr and I also use the sawbird hydrogen line filter to try and increase my chances of receiving a signal. 

Thank you for the response!

Good evening all,

I am currently tearing my hair out at why I keep seeing these peaks along the hydrogen line and I so far have had no success in observing the actual hydrogen line peak.. I was wondering if someone had an answer to the issue at hand here.. Is this normal to see or is there something completely wrong? Any help is greatly appreciated!

Hello everyone! I hope you are all doing well! I just had a quick question about a possible upgrade to my current rig. At the moment I have a nexstar 5se and a ASI 178mm. This rig has a very high focal length which I find is great for galaxies and planetary nebula but with bright and larger nebula it seems to not show anything (I presume this is due to its high focal length). Would it be better to invest into a better mount or possibly getting a refractor telescope with a shorter focal length? Or maybe even a better dedicated astronomy camera?

Update - I have changed back to my original setup since I just realised that the LNB would prevent me from seeing any activity along the hydrogen line..

(Here are some images of the setup by the way, and a screenshot of what has come through so far with the new antenna) 

On 20/07/2021 at 16:53, Ed astro said:

Hi Lucas, 

yes this looks fairly normal. The three bumps in the graph are an artifact of the SDR and will always be there no matter where you point your antenna. 

The hydrogen line is centered at 1420.406 MHz, and you can usually detect it between 1420 and 1421 MHz (the frequency can vary somewhat due to doppler shift). Your graph spans from 1418.1 to 1420.2 MHz, these frequencies are a bit too low and you will likely have missed the hydrogen line.

Could you shortly describe the setup you are using and/ or post an image of your setup?

Best regards,

Eduard

 

Thank you for the response, I have recently changed the antenna I've been using from a custom built one I made to a generic satellite dish to see if this is any more reliable (I still have yet to test it). In terms of the other hardware Im using, I am using some RG59 coaxial cable, a sawbird H1 and a nooelec nesdr smart V4. Im also using SDR# to read the signal.. Thank you for the help!

Good evening, I have been trying to observe the hydrogen line for sometime now and I have this curve using IF average.. At the moment the area of the sky I am pointing my antenna at is not emitting many hydrogen emissions but I was wondering if this graph was normal for this, thanks!

Recently I've been considering getting a light pollution filter for my horribly light polluted skies. However I have a monochrome camera and I'm not sure if any of the Optolong L-pro light pollution filters will have much effect on a monochrome camera or if I should buy something like a Ha filter...

Looking for recommendations!

3 minutes ago, vlaiv said:

I would actually recommend binning in software since there is no difference with CMOS sensor and it gives you more control over the process

Ah I see, is there a link you could attach to do with binning? I've definitely come across the terminology before but never tried the process myself.

23 minutes ago, michael.h.f.wilkinson said:

I have done some DSO imaging with the ASI178MM I have (mainly used for solar white light and Ca-K), but at a much faster focal ratio than the F/10 of the C5. I would certainly get a 0.63x focal reducer, which will make life a lot less difficult for DSO imaging, first of all because more photons hit each pixel, and secondly because guiding errors are reduced. The image below was with am APM 80mm F/6 with 0.8x reducer, LRGB image using a filterwheel.

 

Oh! Do you think this would work with my setup? The reducer and 178MM? Love the image of the cluster! 

3 minutes ago, vlaiv said:

If you take the same scope and put both cameras on and compare them - ASI224 will win / be more sensitive - but that is just pixel size "talking" there.

You can easily turn ASI178 into winning camera even with above same setup - just bin x2 the data. Then you'll have 4.8µm (2 x 2.4µm) vs 3.75µm and that is easy win.

If you have 5" F/10 scope - except for small FOV, you can still get good working resolution with ASI178.

Natively, at 2.4µm pixel size and 1250mm of FL - this gives 0.4"/px. That is way too high sampling rate. You want to be around 1.5" or above at 5". You can bin x4 your data in software but that will make rather small image at 774 x 520.

Alternative would be to get one of these:

https://www.teleskop-express.de/shop/product_info.php/info/p11425_Starizona-Night-Owl-2--0-4x-Focal-Reducer---Corrector-for-SC-Telescopes.html

but that would double the cost.

If you get one of those - then you would be at 0.99"/px and with simple bin x2 - you would get 2"/px - perfect no fuss working resolution and decent size images at 1500 x 1000px

 

Oh! Thank you for all this information this is very useful to me! Do you think it would be a good idea to go for the 178MM and a reducer like the one you linked? I'm happy to see that the 178MM can achieve a good sensitivity since it has such a better sensor size and resolution compared to the 224 (although bin x2 would reduce the resolution).

3 minutes ago, vlaiv said:

Why do you think this to be the case?

QE of 178 is higher than 224 (81% vs 75-80% according to ZWO website)

ASI178 has higher read noise so you need to offset that with longer exposure time, but that will depend on your sky conditions and if you are using cooled or non cooled version (thermal noise can also serve to swamp read noise in non cooled models).

Another factor to consider is of course pixel size - you need to match FL of telescope to get good sampling rate.

If you match sampling rate and offset higher read noise then 178 is more sensitive than 224.

Oh this does change my view quite a bit I hadn't realized that.. I had read on one website it was less sensitive but after what you have told me it makes sense how the 178MM has the potential to be more sensitive. I'm not sure if this would work with my rig and conditions however.

Thank you for letting me know about this!