Extragallactic nebula NGC 604 with small scopes

[Nik271]

I want to share my first observation of a nebula in another galaxy: NCG 604 in M33. This is often quoted as the brightest and easiest extragallactic deep sky object to observe and accessible to even small telescopes. It is a giant molecular hydrogen cloud in  M33 which dwarfs anything in our own galaxy: it is estimated to be 1500ly in diameter, for comparison the Orion nebula M42 is only 25ly across. 

Well, in the past couple of nights I gave it a try and can confirm that it can be seen even in a 4 inch refractor from a suburban location (my garden is listed as SQM 20 but I suspect it is brighter). In fact because it is a small condensed object (1 by 2 arcminutes) I consider it even easier to spot than M33 itself.

The first stage is to get to the location of M33. I use my finderscope, start at Alpha Trianguli and use stepping star to get to a lozenge of 8-th magnitude stars which contains M33.

 

Once in the general area I switch to my widefield EP (24 Hyperion EP) to locate a distinctive quadrilateral at one corner of lozenge. Its easy to distinguish as its courner star ( the one towards the centre of M33) is a wide double.

 

 

Stepping on the side of the quadrilateral towards the double and one step beyond gets you to a 11-th magntiude star. NGC 604 is a dim glow next to it. I could only see it with averted vision and a medium magniication, x70 to x100. The first night I used my 4 inch refractor and it was barely detected. The second night I used my 127 Skymax and it was easier to see occasionally with direct vision due to the extra aperture. I'm sure more aperture will make it even easier. NGC 604 is listed at 14-th magnitude but I don't believe this. I would estimate it at perhaps 12-th magnitude, which is the limit of my 4 inch. I also tried a  UHC filter but it made everything too dark. It may work if you have a larger scope.

 

Anyway, if you haven't tried this one, give it a go! I never thought it possible with my scopes and location.

Clear skies!

Nik

 

 

Edited November 7, 2023 by Nik271
corrected star magnitudes

[josefk]

That's a super report Nik and very encouraging for me because this is on my list for the next dark night. Depending on when that falls i could be trying with an 85mm scope but i assume it will probably need to wait till i have a bigger scope out. There is a lovely in-depth M33 observers guide in the November issue of Sky & Telescope  which is quite inspiring though it very quickly needs a big or very big scope to follow up on. NGC 604 looks like the bright highlight.

Here's a screenshot of the table at the end of that article in Nov-23 Sky & Telescope (it confirms your estimate for Mag12 BTW):

 

[MalcolmM]

Great report @Nik271 and another interesting target for my TODO list! You have made me aware of a number good targets from your posts. I'm still trying to spot Rima Sharp! So thanks 🙂

Malcolm 

[Nik271]

Thank you both, I'm glad if my observations help others! In turn I get a lot of ideas for future observations from fellow SGL-ers, this is what I like most in this forum.

Yesterday the night was clear but not so transparent. I spent most of my observing time on Jupiter but still had another look at NGC 604, this time with my biggest scope,the Skymax 180. I have to say Maks are well suited for this target. The extra aperture and magnification (about x180) helped to see it even clearer. It looked a bit like like a planetary nebula or a very dim globular. I tried my UHC filter this time. It helped a little as the nearby star became  dimmer. The nebula looked a bit larger with the UHC. I coudn't see any structure to it, I guess its needs a proper light bucket for close inspection.

Encouraged by seeing this one I'm going to try NGC 206 next, a star forming  region in M31. From what I can find this one is tougher since it is more diffuse and probably more affected by light pollution. Also  it is  a star association , not a nebula and filters will not help for it.

Keep looking up,

Nik

 

Edited November 7, 2023 by Nik271

[MalcolmM]

Ironically, having mentioned still trying to spot Rima Sharp above, I got it this morning! I've updated your Sharp post with my observation. 

Malcolm 

[John]

Excellent report @Nik271 😁

NGC 604 is one of my favourite targets.

I have managed it with my FC100 refractor on a rather good, dark night last year.

As you say, it's sometimes a little easier than seeing more than a trace of M 33 itself. 

There are other HII regions within M33 to track down (I've not managed these as yet) as Pete Lawrence explains here:

How to observe our neighbouring galaxies - BBC Sky at Night Magazine

Just imaging what NGC 604 would look like if it was within our galaxy ! 😲

 

[josefk]

No detection of NGC 604 last night with 85mm of aperture. My sky was dark but not too clear with strong atmospheric extinction below about 30-degrees so i think lots of damp scatter in the air. I forgot to take an SQM reading.

• M33 was nicely visible at x38 with an exit pupil of 2.3mm but not NGC 604,
• M33 dimly visible at x56 with an exit pupil of 1.5mm but not NGC 604.
• M33 not detectable at x90 and an exit pupil of ~0.9mm and neither NGC 604 but this magnification really framed the squarish hour glass star asterism where TYC 2293-0642-1 is the corner star where NGC 604 should be and HD 9687 is the diagonally opposite star in Nik's mark-up above...

Cloud rolled in before i could start again at the lower magnifications but using UHC. If UHC doesn't do it than i think i need a bit more aperture at that x90 type scale. Good fun.

PS. for calibration i star hopped in from M31 and could see M32 (easy) but not M110 up there (i often can't if its not properly clear).

Edited November 8, 2023 by josefk

[josefk]

sorry to spam your observation Nik.

This is a 35' FOV (x90 for me last night) with the hour glass asterism that helped me lock-in. Those stars are mag9.5...mag10. The corner star where NGC 604 is is mag11.1 but it doesn't feel like the dimmest star in the pattern.

[Nik271]

1 hour ago, josefk said:

PS. for calibration i star hopped in from M31 and could see M32 (easy) but not M110 up there (i often can't if its not properly clear).

Each night I've seen NCG 604 I had a brief look at Andromeda at low power and M110 was also detectable as a dim oval smudge. Last night I was looking again at Andromeda, trying for NGC 206 (no success) and while panning around I lost M110 completely. Looking up I saw high cloud veiling the sky.  I had trouble spotting even M32 after that and packed up. I think M110 is a good test for sky transparency.

In 85mm aperture a magnitude 12 object like NGC 604 will be hard, but I believe possible in dark skies. Good luck!

[John]

When I've observed NGC 604 I have tried UHC and O-III filters but, in my case, I thought they were not making much, if any, difference plus of course they dimmed out M33 altogether. I first spotted NGC 604 with my 12 inch dob. As with many targets, once you have done it, it becomes a little easier to see subsequently, or at least realise that the conditions / scope are not showing it !

I agree that M110 is a good test for sky transparency. On the very best nights here I have seen M33 with 7x35 binoculars. I've never seen it as a naked eye object, though, even under the darkest skies.

 

[Franklin]

16 hours ago, John said:

Just imaging what NGC 604 would look like if it was within our galaxy ! 😲

 

I thought you were visual only?😁

Edited November 8, 2023 by Franklin

[John]

7 hours ago, Franklin said:

I thought you were visual only?😁

Darn - you got me there ! 

My worst nightmare 😬

[MalcolmM]

So armed with @Nik271's directions, my Mewlon 180, and a Masuyama 32mm I gave this a go tonight. At 7.30 the sky was not great (I could only just make out Triangulum), but the directions were easy to follow and I spotted the 11th magnitude star, but not NGC604. I swapped the 32mm for a Masuyama 20mm and with averted vision was able to glimpse it occasionally. M33 was not visible at all. 

I tried again later at 10.00 when the sky looked a bit better, still not great, but this time I could see it with direct vision. It appeared like a small, irregular planetary Nebula. Also, with direct vision, I could see M33.

All in all, a very satisfying observation. Thanks @Nik271 for the tip and directions!

Malcolm 

[RobertI]

Great write up Nik, it’s really inspired me to find it from my back yard. I viewed M33 through a 16” dob at Kelling recently  and NGC604 was very bright and easy to see. I could also see another nebula which I assume to be NGC595 which was almost as bright. Looking forward to tracking it down. 

[John]

I managed to get NGC604 with my 100mm refractor tonight at 64x. Pleasing result given the weather we have had recently.