16 replies to this topic

[gnowellsct]

Some time ago, as in decades, a friend of mine excitedly showed me a diagram of 10 gears that interlocked and had a crank on one end. He said that if you turned the gear on the left side The ratios were such that the gear at the extreme end would have to turn at the speed of light.

I said this was a great idea and that he should manufacture a few and sell them in this manner: SPEED OF LIGHT MACHINE: IT DOESN'T WORK! And include little pamphlet explaining why. It would be a great thing to sell in science shops, if any science shops still exist.

In similar manner, I propose the The first and probably still most famous Hubble deep field as a deep sky observing object. THERE'S NOTHING TO SEE. Well, not quite.

Last night we had a star party with about 15 people in attendance. The original Hubble deep fields coordinates are RA 12h 36m 49.4s and dec +62° 12′ 58″. Megrez and Phecda In the bowl of the Big Dipper point to it. Take the distance between the two stars and go that far again, you are in Hubble deep field territory.

In the c14 at 98x with a 40 arc minute field of view, you see a scattering of a dozen stars perhaps 12th magnitude and fainter. They are absolutely unremarkable. The Hubble deep field is only two and a half arc minutes long so even with the stars there's plenty of space to hide the deep field in there. But certainly one of the things to be remarked in the Hubble deep field is the absence of stars that are so bright they would ruin the capture.

And of course you are well off the galactic plane, that's why the stars are sparse.

Star hopping to the Hubble deep field would be a real act of virtuosity as you are looking for space with no distinguishing features. There's no "aha there it is!" thing to let you know you are in the right place. I arrived at the destination using Argo Navis in RA Dec mode.

Well quite a few people who normally feed on messiers, double stars, and bright NGCs eagerly lined up to look at nothing at all.

I hope to release my book "Exploring The Hubble deep field for the amateur astronomer" in the near future.

Greg N

[Astrojensen]

I wonder how big of a telescope it would take to visually glimpse some of the brightest galaxies in the Hubble Deep Field? 

 

 

Clear skies!

Thomas, Denmark

[TOMDEY]

Excellent! Back when I observed almost every clear moonless night with my trusty old 29-inch telescope --- I would intentionally spend 10% of the time fully dark-adapted on a "blank" spot in the sky --- and examine it for quite some time. There was almost always something there --- some dim stars and frequently one or more galaxies. My current big scope is 36-inch and I use a Gen3 Night Vision eyepiece, which ~penetrates~ 1+ magnitudes deeper. My conclusion is that... wherever you look... there are galaxies there. Hubble of course confirms this and shows a lot of detail. Even more so --- JWST!    Tom

[Jon Isaacs]

Robert Williams used his time as director to image an area with nothing for about 100 hours with a 2.4 meter scope in space.  

 

I think it's reasonable to assume that a 0.35 meter telescope used visually would show absolutely nothing.

 

Some years ago I attended a conference where Dr. Williams was the keynote speaker. The topic was the importance of taking risks. 

 

Jon

[gnowellsct]

Dr Williams took a well informed risk. In the late '80s some younger astronomers were using 80 and 100 inch telescopes to do what they called "pencil sampling", long exposures of very narrow fields. Every time they did it they found something. The surprise of the Hubble deep field was that there was so MUCH.

Of course if one studies the Hubble deep field there are a number of foreground galaxies which are only 6 to 8 billion light years away. They're not as interesting, from some points of view, is the red barely visible pixel dots in the far background. Those are the ones at 13 billion light years and the subject of intense interest in cosmology.

When one is wondering what it would take to actually visually detect something in the Hubble deep field it would matter a great deal whether the objective was to observe only the foreground galaxies or whether you really were crazy enough to think that with a big enough telescope you could observe the red dots in the background.

For amateur purposes we are talking about pointing telescopes at the region that will provide, In most scopes, anywhere from 20 arc minutes to a couple of degrees of sky and there will be activity. As I mentioned I saw about a dozen faint stars.

But this is just saying that the "Hubble deep field" for my purposes is about a 40 arc minute patch of sky in which I know the Hubble deep field is situated. In the actual 2 and 1/2 arc minute portion there is nothing.

The 40 arc minute section of sky I was inspecting had room for multiple Hubble deep fields and I surmise, from the absence of nearby bright stars, that they would be more or less equally plausible patches of sky for a long exposure.

I hate to say it but after going through all the trouble to locate and observe it I forgot to look at it in my 92 mm. My personal "Hubble deep field" would be considerably larger in that scope, although if I boosted the power to 100x it would be the same area as I was observing in the c14. I will have to await another occasion.

The Hubble deep field shows a number of foreground stars that are in our own galaxy. Those might be visually identifiable at the eyepiece of a very large instrument.

Greg N

 

Edited by gnowellsct, 24 June 2025 - 04:34 PM.

[gnowellsct]

Here's a map of the Hubble Deep field area.  The inner circle is the C14 40 arc minute field of view, the outer circle is a 2.5 degree field of view.  10th magnitude NGC 4605 is an easy "rest stop" before proceeding to the deep field.  NGC 4545 might also serve as a "rest stop" but it's 12th mag and would be less accessible to smaller scopes.  Most any scope in use could pull in NGC 4605 but I wouldn't bet the same is true for NGC 4545.  

 

--Greg N

 

[Keith Rivich]

I have attempted this several times with my 25" scope and Larry Mitchells 36" with mixed results. The HDF sits in a parallelogram of four stars that span around 12 arc minutes. These stars are in the 12 to 14th mag range. As Greg states it is not an easy star hop.

 

There are a couple of test observations we used to gauge what might be possible. Around 8' east of the HDF is a ~17.5 mag galaxy. Small but non-stellar. Box checked, we could see it in both scopes. Right next to the HDF there is an arc of 4 stars all around 19th magnitude. It really helped printing a chart in Megastar with the USNOA-2 option! I had much trouble in the 25" seeing these stars. Very fleeting. In the 36" they were just visible with averted vision. 

 

With this arc we could center the HDF with very high confidence. 

 

I saw nothing in the 25". Just empty space. In the 36" we could just see some lumpiness to the empty space. Nothing we could grab hold of and say "yes, we saw a galaxy". 

 

We had about a perfect night as we could have hoped for and just saw lumpiness. Not a positive observation! 

 

IIRC Jimi Lowry and others did manage to pick up a couple of the brighter galaxies in his 48". Perhaps he can add to this.

[gnowellsct]

Fellow observers of nothing. This is awesome. I thought I was the only one.

[gnowellsct]

I think the lumpiness is a hallmark of an observation "at the margin." I successfully viewed Pal 14 in my 14" from a very dark site in the Adirondacks. I had a map printout and in the right angle asterism where the map had it I could see nothing. I made a little drawing and put a question mark near the lumpiness or as I described it "disturbance in the force." Later on I checked it in a sky survey and found out that my observation had been correct and the map was wrong by an arc minute or two. I actually was able to contact some sky map people in AZ (Lowell observatory) and get it corrected. But insofar as there are many dozens or hundreds of star maps I doubt the error correction has propagated everywhere.

I've noticed the lumpiness is also related to stars at the margin. In the region around M56 (not m57) the lumpiness is so thick I call it "galactic pavement." I find it very intriguing.

Greg N

Edited by gnowellsct, 25 June 2025 - 07:24 AM.

[allgoodgifts]

Think I'll try the Hubble Deep Field Star Hop Challenge!

[Keith Rivich]

Think I'll try the Hubble Deep Field Star Hop Challenge!

You shouldn't have to much problem with the 10". Even though the HDF is pretty barren there are enough brighter stars in the vicinity to help with your star hop.

 

If you want truly barren skies there are a few areas in nearby Bootes that make the HDF star field look like a crowded subway car!

Edited by Keith Rivich, 25 June 2025 - 05:10 PM.

[gnowellsct]

If you want truly barren skies there are a few areas in nearby Bootes that make the HDF star field look like a crowded subway car!

And of course there are many deep fields now. But I'm not sure a list of the top 10 or top 100 deep fields would attract a great deal of attention. Observing nothing has a great deal of novelty, but it can only go so far.

Edited by gnowellsct, 26 June 2025 - 07:23 AM.

[Keith Rivich]

And of course there are many deep fields now. But I'm not sure a list of the top 10 or top 100 deep fields would attract a great deal of attention. Observing nothing has a great deal of novelty, but it can only go so far.

Agreed. 

[WillR]

If you were able to observe the Hubble Deep Field with the Hubble and an eyepiece- I other words a 2.4 meter telescope in space, outfitted with an eyepiece, and the focuser somehow positioned in an air chamber, you still wouldn’t see anything. After all, this was 100 hours of imaging.

 

So my question is have amateurs attempted to image the HDF from earth in their instruments? I have to assume many have. How deep did they go?

[gnowellsct]

If you were able to observe the Hubble Deep Field with the Hubble and an eyepiece- I other words a 2.4 meter telescope in space, outfitted with an eyepiece, and the focuser somehow positioned in an air chamber, you still wouldn’t see anything. After all, this was 100 hours of imaging.

So my question is have amateurs attempted to image the HDF from earth in their instruments? I have to assume many have. How deep did they go?

There are foreground stars and galaxies that are "only halfway out." I think it's conceivable that amateur class instrument with a long exposure could pick up something or other. I might put money on it, but I wouldn't bet the farm.

[Ptarmigan]

If you were able to observe the Hubble Deep Field with the Hubble and an eyepiece- I other words a 2.4 meter telescope in space, outfitted with an eyepiece, and the focuser somehow positioned in an air chamber, you still wouldn’t see anything. After all, this was 100 hours of imaging.

 

So my question is have amateurs attempted to image the HDF from earth in their instruments? I have to assume many have. How deep did they go?

I have seen people who have imaged Hubble Deep Field with their own telescope. The brightest galaxy around magnitude 18 to 20. A search on Hubble Deep Field here will reveal people have imaged the Hubble Deep Field. I have seen it myself with EAA.

Edited by Ptarmigan, 29 June 2025 - 08:55 PM.

[Ptarmigan]

And of course there are many deep fields now. But I'm not sure a list of the top 10 or top 100 deep fields would attract a great deal of attention. Observing nothing has a great deal of novelty, but it can only go so far.

I can imagine if you pick a random spot away from the Milky Way dust lanes, and do long exposures with camera. You will likely see distant galaxies and many are likely uncatalogued.

 

The late Paul Boltwood imaged an area in Serpens. It is known as the Boltwood Deep Field. It goes down to over magnitude 24.

https://apod.nasa.go...d/ap990414.html

https://astro-canada...ul_boltwood-eng