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Old 08-03-2020, 02:35 PM
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GUS.K (Ivan)
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QSO in Indus.

Anyone here have luck spotting QSO 2204-573 in Indus. Simbad has it at Vmag=17.4, so might be visible in an 18 inch scope on a night of good seeing and at high magnification. Redshift is Z=2.73 so a whopping 11.3 GLY(Ho=70.4).
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Old 08-03-2020, 08:59 PM
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Hi Ivan,

Nope, not had a go at that one. In the same field as a nice, bright marker galaxy (NGC 7205), so finding the right spot will be easy, seeing it at Vmag +17.36 will be an altogether different bucket of fish.

Will put it on the list of things to do in September with Brontes.

Best,

L.
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Old 09-03-2020, 08:14 AM
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Thanks Les, should be relatively easy in the 25 inch. Might be too much of a challenge for the 18 inch. The author of the artIcle regarding this QSO saw it through a 17.5 inch scope, might be possible.
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Old 09-03-2020, 11:47 PM
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Hi Ivan,

Quote:
Originally Posted by GUS.K View Post
... should be relatively easy in the 25 inch.
Hmmm ... not so sure I would call Vmag +17.4 "relatively easy" in nearly any 'scope. I've seen several stars in the mid to low 17s in the 25, but they take some concentration, moderately high magnification, care and good conditions (seeing as well).

But, I'll definitely give it a shot ...

Best,

L.
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Old 10-03-2020, 08:00 AM
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GUS.K (Ivan)
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Thanks Les, looks as if this might be close to impossible with the 18 then, even with the right conditions, I think it's a big ask. I've gone to mid 16th mag with the 18 and that was hard work, 17 mag might be in the realm of averted imagination maybe?

Last edited by GUS.K; 10-03-2020 at 08:38 AM.
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Old 10-03-2020, 02:11 PM
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Rainmaker (Matt)
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I think Les might have an advantage over us Ivan, I was having a look around Billimari on Thursday, not much artificial light to hamper viewing out there.......

16.5 is about as dim as I have got reliably from the 18.... out at Cookamidgera and Coolah
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Old 10-03-2020, 08:09 PM
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Hi Matt, mid 16th mag seems to be my limit as well, but reading reports from others reaching early to mid 17th mag (realistic or not) in 18 inch scopes in good seeing makes me want to try myself, maybe in the right conditions it might be possible, I won't know if I don't try.
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Old 14-10-2020, 07:00 AM
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Had a go at spotting the quasar on Monday night. Seeing was the best I'd had in a long time and transparency was very good as well. I was able to use just over 500x in the 18 inch dob and NGC 7205 (very close to the quasars location) showed noticeable mottling and the spiral arm was very distinct. Moving to the quasars field, I was able to locate all the field stars shown on the finder chart, the faintest magnitude I could see with direct vision was a 16.4 mag star near the quasars location. With averted vision, I could see fainter stars intermittently in the area of the quasar but wasn't able to confirm it positively. I have made a more detailed chart to try again at the next opportunity.
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Old 15-10-2020, 01:15 AM
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Hi Ivan & All,

Thanks for the reminder -- I see if I can have a crack at it sometime in the next month or so.

Yep, where I observe the conditions are at least very good. Most northern hemisphere observers would give their right arm for this sort of sky darkness. BTW, I'm not right in Billimari, if you can see Billimari & Gooloogong on a map, I'm almost at the mid-point between the two. There is a bridge (Davison's Bridige) over the Lachlan near Merriganowry (locality) and I'm about 1.5km as crow flies from that on Cultowa Lane, but about 40m up in elevation. The nearest fair-sized town is Cowra (10,000 odd people) 26km away as the photon flies (36km as the road goes). Billimari itself is all-but 5km away and has four street lights and 16 homes.

I am also fortunate to have very considerate neighbours when it comes to lighting and light-pollution. My next-gate neighbour is also an amateur and ASNSW member having worked for many years at Tasco over at Brookvale.

Best,

L.

Last edited by ngcles; 15-10-2020 at 01:29 AM.
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Old 15-10-2020, 08:42 AM
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Let us know if you succeed. You're at an advantage with the larger scope and better location than me. It might seem like a waste of time to some, but I enjoy tracking down these ancient objects from the distant universe. If anything, I'll know the limiting magnitude of my scope versus different seeing conditions.
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Old 16-10-2020, 11:30 PM
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Thursday night ended up being clear with great seeing so armed with a new chart, gave the quasar another shot. After locating epsilon Indi and moving on to NGC 7205 (10 mag) I moved over to the field and spotted the asterisms on the main chart. Once finding the line of stars in the middle I then looked for the 16.75 mag star at the right end of the line. Spotted with averted vision after a few minutes of trying(faintest star seen to date through the 18 inch scope) I then looked for the 16.75 mag star just above the quasar and duly spotted it with averted vision (it forms an isoceles triangle with the two stars under the quasar).
Next, tried for the quasar by noting its location in respect to the two stars below it- 15.65 and 14.45 mag with which it forms an equilateral triangle.
After trying for a few minute the quasar was spotted first as a light haze then as a point source on consecutive sightings. Over the course of a half hour, the quasar was spotted a half dozen or so times.
Towards the end of the night I revisited it again and was able to spot it a few times over the course of 20 minutes.
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Old 19-10-2020, 01:28 PM
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Hi Ivan,

Congratulations and well done -- I will have a crack at it sometime in the next month.

Have been to the SIMBAD page whcih provides a recessional velocity of -259,486km/sec (just over 86% of c). Given that recessional velocity and Ho assumed at 70.4km/sec/MPc gives a look-back time of 12Gyr (+/- a little bit) -- when the Universe was only about 1.8 Gyrs old or ~13% of its present age.

http://simbad.u-strasbg.fr/simbad/si...bmit=submit+id

Best,

L.

Last edited by ngcles; 19-10-2020 at 01:54 PM.
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Old 19-10-2020, 10:19 PM
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Hi Ivan & All,

Can add a confirming observation of QSO 2204-573 tonight just before 10.30pm, 63.5cm x347. SQML reading was 21.88.

Using my 63.5cm f/5 Newtonian tonight about 10.20pm, from NGC 7205, I slewed the ‘scope 20 arc-minutes N locating the wide, magnitudes +11/+11 pair separated by about 30” (marked in the image). This is where I swapped from moderate (x195) to high magnification (9mm TI Nagler @ x347 and 14 arc-minute diameter true field in my case). QSO 2204-573 is just 4 arc-minutes WSW from this pair and less than an arc-minute NE of the centre star in a compact straight-line of three stars (underlined in the image), all about magnitude +14.5 – +15.5.

Pretty simple thus far, now it gets tricky: QSO 2204-573’s true V magnitude is +17.2! I have seen a number of stars as faint with this telescope, but they take concentration, perseverance and a very dark, transparent sky. Patience and a number of minutes with no light of any sort (to permit profound dark adaptation) is mandatory. After I was convinced I had the spot precisely centred and was fully dark-adapted, I observed intently for about five minutes and during that time I glimpsed QSO 2204-573 momentarily at least twenty times. Toward the end, I could nearly hold it continuously with averted vision. The small, apparently edge-on galaxy PGC 129038 (marked on the image) was similarly seen intermittently and was probably slightly easier. This galaxy has no calculated recessional velocity and its distance is not known. It has a B magnitude of +16.1 so its true V magnitude is approximately mid-15s – but is an extended (ie non-stellar) object with lower surface-brightness than the QSO.

Why did I bother to sleuth-down QSO 2204-573? It has a measured redshift of 2.73 and a recessional velocity of 259,486km/sec (yup, that’s just over 86% of c!). Derived from that, adopting a Hubble constant (Ho) of 70.4km/sec/Mpc and adopting some standard assumptions as to our Universe’s geometry, implies a distance/look-back time of 12 billion light years (+/- a little bit) – or about 87% of the way across the observable Universe. The light I saw tonight was emitted when our Universe was no more than the equivalent of a pre-pubescent child -- ~1.8 Gyrs old or approximately 13% of its present age.

Thanks for the heads-up Ivan.

Best,

L.
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Old 20-10-2020, 06:33 AM
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Thanks Les and congratulations on the successful observation. I forgot to mention my observations were made with a 4.5mm eyepiece (511x) with a TV coma corrector(1.15x). I did try with a 3.5mm EP(657x) which was still quite useable but it meant nudging the scope more frequently to keep the field centred. To make sure I was not misidentifying the quasar with another field star I made note of the pattern of two overlapping triangles with the quasar forming the apex of an equilateral triangle and a 16.75 mag star forming the apex of an Isosceles triangle. That way I was able to confirm the quasars location. What also helped in my situation was memorising the finder field and not having to look at a chart and stuffing up my dark adaption. Knowing I can get down to at least the early 17th magnitude, my next target will be a quasar in Eridanus (HE 0435-1223) not far from Rigel, which I've already scoped the field out for last week.
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