Whitepeak Observatory, Tacoma, WA

Calibrated Crater Sequence Images


Crater sequence images available for download.

Four areas are now available:

1) Mare Humorum
2) Clavius
3) Ptolemaeus
4) Mare Nectaris/Fracastorius

I may make one or two more of these (western Mare Fecunditatis?) but the four done (Petavious, Fracstorius/Mare Nectaris, Ptolemaeus and Mare Humorum) are it for now. (Five are done including Chuck Wood's one of Serenitatis located: here

All these were made using the Bowker & Hughes Lunar Orbiter atlas scaled images, sizes measured to nearest 1/128th of an inch using steel machinist's scale and 8x magnifying loupe. I consider the sizes accurate to +-100meters on craterlets <4km diameter, +-200 meters otherwise. Note: Imaging artifacts (over/underexposure, variable degrees of focus) on the CLA images used may make some craterlets appear larger or smaller than they appear on the higher resolution Orbiter images. Some craterlets are not resolved on the images except as undifferentiated 'spots'. Nevertheless, their positions are accurately indicated. I tried to measure only craters which are simple in form and not sub-resolution multiples or ruined illregular craterlets. I used the same labelling scheme as Chuck Wood used in his sequence chart; sizes/location info in white, names in black.

Small format: jpegs (~250KB) are available below:

Mare Humorum:

Mare Nectaris/Fracastorius:

Ptolemaeus:

Clavius:

Large format: images suitable for hardcopies (300dpi) are available for download; they are free for any use as far as i am concerned. Caution: they are large (8-10MB) files:

Mare Humorum:

Mare Nectaris/Fracastorius:

Ptolemaeus:

Clavius:


NOTES ON USING THESE CHARTS:

These charts can be used to assess both the state of seeing and available resolution during visual observations.

*For "best optimal seeing" and/or ground resolution assessment*

Craterlet size resolvable as a craterlet/depression, not an undifferentiated spot:

3.8-4km = ~2" arc best seeing/resolution
2.8-3km = ~1.5"
1.8-2km = ~1.0"
1.75-1.5km = 0.8"
1.3km = 0.7"

Above based upon mean lunar diameter where 1.86km = 1.0"arc. Resolution of craterlets as undifferentiated spots will be higher by a factor of at least 2 from the above figures, depending on local contrast.


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