Lunar Observing Report February 12th 2011- Lichfield - 66% Waxing Gibbous

It was with some trepidation that I ventured out on Saturday after my last experience with the new Televue 3.7mm Ethos. Would I suffer the same problems of kidney beaning blackouts and that horrid yellow/red ‘flaming halo’....? I’d had some thought provoking responses from far more 1 experienced observers to my query on the American forum; ‘Cloudy Nights’. Suggestions ranged from making sure the eyepiece was seated correctly in the diagonal, atmospheric distorsions, faulty eyepiece etc, yet the most common theme appeared to be the link between my scopes f/ratio (greater than f7), a small (less than) 0.5mm exit pupil, ultra wide (110-FOV) with a large eye lens - as well as trying to view a bright full moon too!

As one commentator stated, ”the brightness of the full moon causes your eye's pupil to constrict, which makes it all too easy to sample only a portion of the (already small), exit pupil with your eye pupil (and interfering with eye placement), especially when you're looking 55 degrees off axis! Before trying to look around, I'd suggest trying to look on axis and letting your peripheral vision soak in the 110 degree field.” Also, “diameter of exit pupil figures are mostly consigned into side-to-side tolerance for eye positioning, and typically the manifestation is not so much blackouts but dimming of the view as one clips part of the light for any given point by letting the eye wander too much to one side or the other. Once the exit pupil gets this small, however, the difference in size is not very significant to eye positioning. What's more significant is 110 degrees versus 100 degrees, since the larger the apparent field the tighter the tolerance for the distance your eye must be kept from the eye lens. That's where the blackouts come from typically, i.e. getting too close to the lens, since this exacerbates the effect the slightest side-to-side positioning error, some of which is probably inevitable. ....

Lastly, “as the exit pupil grows smaller, the width of the light-cone within which the image properly converges decreases, even though a relatively slower (say f/8 vs f/6) scope will have a longer vertical (i.e. on-axis) zone within which the image appears to come into satisfactory focus; even so, the width of that zone narrows as you move axially in either direction from the point of ideal focus. So, even modest mis-alignments of your eye and the exit pupil can induce seeming eyepiece misbehaviors such as blackout zones and flares around the edge. An ultra-wide AFOV eyepiece with a big eyelens such as the 3.7E doubtless requires quite a bit more critical internal bending of light through much wider lenses than a significantly narrower AFOV eyepiece with a much smaller eyelens. One of the most impressive things about TeleVue's eyepiece design quality is how generous, relative to exit pupil and eyelens Eratosthenes size, the forgiving zone of aberration-free view is, but there comes a point for every person's eyes where the small exit pupil size simply falls too far below a critical size”. 1 So, with all this taken on board, I decided to set up early evening whilst the sky was still blue - apart from being something of a novelty to look at the moon against a blue (rather than black background), it would give the scope and eyepiece plenty of time to cool, I‘d be able to see what I was doing (for a change), there would be less contrast and glare (so hopefully less eye problems) and I thought I may have a go at doing some quick sketches this time...

Andy had kindly brought me a year’s subscription to the BBC’s Sky at Night Magazine for Christmas, and the January edition had a feature on Apollo 14, so after my recent success at identifiying the Apollo 15 landing site, I set myself the goal of finding NASA’s preceeding Apollo exploits... This time I made sure that the 2” barrel extension was seated properly within the 2” Televue Everbright diagonal. From the outset the experience was far more enjoyable - less bright (so I was not squinting through the eyepiece). I focused in on the terminator around the large crater formation Eratosthenes. Unlike last time (full moon), there was a healthy dose of contrast - rich blacks and ultra sharp whites (I can only compare the whites to being cooler than the 31mm Nagler’s noted warmer whites and my Takahashi 5 and 7.5mm LE eyepieces which also display a warmer tone). I swapped between the Taks and Ethos and could not see any loss 1 of light from the extra glass within the Ethos. In fact, sharpness and contrast appeared slightly higher in the Ethos, but that was probably down to the additional magnification and cooler tone.What cannot be dismissed though is absolutely huge field of view compared to the five element Erfle design of the Takahashi eyepieces that only offer a 52º apparent field of view. This definitely does allow far more time to concentrate on your target (well to allow the vibrations to settle and find that critical eye placement!)

I could only see a small amount of the ‘flaming yellow/orange’ halo out at the extreme edge, say between 20 past the hour to a quarter to.... It would virtually disappear as I made a concerted effort to re-centre my eye and ‘force’ it open... The halo was no where near as off putting as before - and I would not want to put anyone off the purchase of such an eyepiece now (it’s not going back to Telescope House or being put N Eratosthenes up on ‘UK Astro Buy and Sell’ anyway!) As I moved around the lunar surface I did not note any flaring, yet I still experienced a small amount of kidney beaning.... as I spent more time observing I was able to get this under control E W by ‘fixing’ my eye placement. It was slightly more problematic later when I tried my hand at some quick sketching - as I looked to and fro between S eyepiece and sketchpad I had to re-find that critical zone where the 1 blackouts would disappear.... perhaps for that need, ‘Uncle Al’ at Televue will have to produce a 4.something - 5mm Ethos!

Over time I tried to relax and allow my eye to find a comfortable, centralised position without trying to take in the whole field. Once ‘centred’ I took my time to move my eye in and out of the rubber cup and find that proported 15mm of eye relief - to be found somewhere between the large concave eye lens and the (non- 2 adjustable) outer regions of the rubber eyeguard. It was only then that I rotated my eye around to take in the field. I could manage a small amount of ‘head’ movement, but, too much and the halo would start to re-appear and 3 the blackouts would start to re-form. I think I am at the extreme envelope of magnification and FOV with this eyepiece/f8 focal ratio as the American * guys had mentioned. Certainly on those few exceptional nights we enjoy in 4 the UK, I have been able to use my 2.8mm, 3.6mm Takahashi eyepieces with some success as well as ‘Powermate’ the 6mm Ethos (a rather heavy and 5 cumbersome combination for my liking), so I am leaning towards the extra Mare FOV being the problem rather than magnification and exit pupil. 6 Nubium 7 So, onto the observing report for the evening! The area to be observed happened to be not far from the previous observing session. Using the 60 mile wide crater Copernicus (1) as a reference point I headed down to a half way point ( approximately 18° West 6° South) between the distinctive set of craters;* Herschel (2), ‘trio craters’ Ptolemaeus (3), Alphonsus (4), Arzachel (6) and Alpetragius (5).

Herschel is at the head of this multiple crater formation situated on the northern slope of Ptolemaeus - about 25 miles in diameter with high terraced walls (about 11,400 deep), so has a good amount of shadowing within it. Its floor dominated by a central mountain that glints in the sunlight. If you study this feature closely you can see the 8 mile crater Herschel G that just takes the slightest of nicks out of its larger cousin’s bottom!

Much larger (yet looking far shallower and therefore lighter), is Ptolemaeus. Stretching over 93 miles and estimated to be somewhere in the region of 3.92-4.55 billion years old.... Its flat looking floor does give up a series of ghost craters and small craterlets to the determined/patient observer (just visible is craterlet Ammonius - 5 miles diameter at the 10 o’clock position - at the top left of the red number 3).

Further south is the far more interesting crater Alphonsus (4). Alphonsus is estimated to be in the region of N 3.9 billion years old and shares a good section of its northern walls with Ptolemaeus. Smaller at 71 miles wide, it has high terraced walls with a deeply ridged protusion that extends into the higher crater on the eastern (left side). E W There is scarring at the bottom area where there appears to be a crater hole punched out of the south wall (6 o’clock position). Its floor has a central S mountain peak.

To the right (West) of Alphonsus lies Alpetragius (5). Embedded in a highly 2 textured region that straddles its larger neighbours. It is easily identified thanks to its distinctive dark shape - due to a depth of 11,800 ft / 24 mile wide ratio. 3 It sports a large percentage of shadow across its high terraced walls and floor * that includes an imposing central mountain - truely a beautiful sight. Arzachel (6) is the last of the remarkable trio of larger craters. Dating from the 4 Lower Imbrian geological period (3.8 3.85 billion years old). It is 59 miles in diameter and about 10,900ft deep. Again it has high terraced walls, a flat floor 5 with a 1500m high central peak. To the 10 o’clock position from the mountain 6 can be made out craterlet ‘Arzachel A’ that is about 6 miles wide. 7 Mare To finish off we must look to position (7), although for an observer there are Nubium plenty more lunar features to keep one interested around this region.... At (7) lies what appears to be a crack in the eyepiece, or perhaps a hair! Rupes Recta ‘Straight Wall’ is more than 3 billion years old and cuts a 67 mile long line across the surface of the moon. It is described as a rectilinear 900ft fault in the lunar crust, to be found on the Eastern bank of Mare Nubium. Through N the eyepiece it looked as sharp as a knife and jet black.

Next it was time to find the Apollo 12 and 14 landing sites so I closed in to W the region marked with an ( ). The large circular depression (8) is E Fra Mauro, dating from the Pre-Nectarian* period (3.9 - 4.5 billion years S old). It is 58 miles wide, forms an interesting trio with Parry and Bonpland craters beneath it, and contains a fair few pot-marks to search for!

18 Parry (9) crater lies to the South-East of Fra Mauro and shows far more distinction due to its increased depth of 1,700ft (and is just about half the size (29 miles). Its northern walls appear quite high in the eyepiece - almost mountainous whereas to the south they almost dissapear into the surrounding tundra. I was able to easily spot (and sketch) craterlet Parry E (@ 4 o’clock) a 4 mile chunk taken out of Parry’s South-Western wall. Further west is Bonpland (10). Like Fra Mauro it is described as a 17 ‘walled plain’ and dates from a similar era. Approximately 36 miles across and with southern walls which almost disappear into the surrounding Mare Cognitum. 8 16 (12) Tolansky, is 8 miles wide and 2,700ft deep so therefore well defined in the eyepiece. With a deep black shadow and opposing bright 15 highlight. To its right (East) was what looked like a horseshoe (11). 14 (11) Parry M. ‘Horseshoe like’ as it appears to have no Northern walls. Beneath it - I could visualise another fragmented horseshoe shape that made a sort of corridor towards crater Guericke (13). Technically this is 9 10 regarded as another walled plain of 35 miles in diameter and said to have a wrecked circular formation. From my rough sketch I was later 11 able to work out that I could make out two large craterlets contained with the South-Western region (one marked H ‘Guericke H’ in the 12 inset is 4 miles wide), but I’m not sure what the designation is for the one on the right.

Certainly I noted the depression to the right that extendes beyond the South-western Walls - ‘Guericke F’ that is 12 miles across. I also 13 drew a circle out of the south wall.... was I mistaking this with the glint from Guericke H, or perhaps this was just the light playing on the outer rim of the parent crater... more likely it was ‘Guericke H’ and what I marked down as H was actually the light/shadow playing off that dark bump that you can see above ‘H’ in the inset.... I shall have to return some time (and make better notes!!!) Not annotated to the south west is another reasonably sized crater (9 miles wide), ‘Guericke B’. So now the hunt was on for the Apollo landing sites. Across from crater Tolansky (12), lies 4 mile wide crater Kuiper (14). This 4,000ft deep hole was quite small to determine, yet it does help that it lies slap bang in the middle of Mare Cognitum! This being a fairly dark (and flat region), does help when trying to pick out a small but fairly dark crater. A useful marker to verify craterlet Euclides K (18) to the north. ‘Useful’ as we shall see in a minute!

18 From the sketch it lies above a mass of ‘scribble’ - I believe that represents(!) the geological 14 mile ‘dome’ feature Riphaeus 1.

Other prominent craterlet markers to aid amateur observers with trying to identify Apollo 12 and 14’s landing sites were Fra Mauro A (15), Fra Mauro C (16) and Fra Mauro B (17). In fact the Apollo 12 site can be roughly found by imagining it is the upper most point of an imaginary 17 triangle between Fra Mauro B and Euclides K.

To the West, above the outer lying reaches of Fra Mauro and within the 8 16 rough/lighter textured area of this crater, I was able to narrow down the location of the Apollo 14 landing site... well, close enough for a relative 15 beginner to be comfortable with...

14 Apollo 12 launched on schedule from Kennedy Space Center, during a rainstorm. It was the first rocket launch attended by an incumbent US president, Richard Nixon. 9 10 Thirty-six-and-a-half seconds after lift-off, the vehicle triggered a lightning discharge 11 through itself and down to the earth through the Saturn's ionized plume. Protective circuits 12 on the fuel cells in the service module falsely detected overloads and took all three fuel cells offline, along with much of the CSM instrumentation. A second N strike at 52 seconds after launch knocked out the "8-ball" attitude 13 indicator. However, the Saturn V continued to fly correctly. The loss of all three fuel cells put the CSM entirely on batteries. They were W unable to maintain normal 28V DC bus voltages and the AC inverters dropped offline. These power supply problems lit nearly every warning E light on the control panel and caused much of the instrumentation to malfunction. S EECOM (Electrical, Environmental and Consumables Manager) John Aaron remembered the telemetry failure pattern from an earlier test when a power supply malfunctioned. Aaron made a call: "Try SCE to aux". This switched the SCE to a backup power supply. The switch was fairly obscure and neither the Flight Director, CAPCOM, nor Commander Conrad immediately recognized it. Lunar module pilot Alan Bean, flying in the right seat as the CSM systems engineer, remembered the SCE switch from a training incident a year earlier when the same failure had been simulated. Aaron's quick thinking and Bean's memory saved what could have been an aborted mission. Bean put the fuel cells back on line, and with telemetry restored, the launch continued successfully. Once in earth parking orbit, the crew carefully checked out their spacecraft before re-igniting the S-IVB third stage for trans-lunar injection. The lightning strikes had caused no serious permanent damage.

Initially it was feared that the lightning strike could have caused the command module's parachute mechanism to prematurely fire, disabling the explosive bolts that open the parachute compartment to deploy them. If they were indeed disabled, the command module would have crashed uncontrollably into the Pacific Ocean at the end of the mission and killed the crew instantly. Since there was no way to figure out whether or not this was the case, ground controllers decided not to tell the astronauts about the possibility!

Landing The Apollo 12 mission landed on an area of the Ocean of Storms that had been visited earlier by several unmanned missions (Luna 5, Surveyor 3, and Ranger 7). The International Astronomical Union, recognizing this, christened this region Mare Cognitum (Known Sea).

The second lunar landing was an exercise in precision targeting, using a Doppler effect radar technique developed to allow the pinpoint landings needed for future Apollo missions. Most of the descent was