4.9.1-1 - Apollo 17 Day 1 launch and EPO

Apollo 17’s launch day is a little different to the others in this series, not just because it was a night one. The crew took far more photographs in Earth Parking Orbit (EPO) than previous missions, and while some are easy to locate, others require a little detective work that necessarily involves including later images out of sequence. It also means we have to split day 1 into two parts to make it more manageable - see here for the post-TLI section.

To do this detective work we have a number of tools at our disposal, namely the known EPO track of the orbiting Saturn IVB stack, the weather satellite record, the mission transcripts, and the famous ‘Blue Marble’ image (as well as others taken after Trans-Lunar Injection, or TLI) that shows the broader context of the daylight illuminated planet below them.

Let’s begin at the beginning.

Apollo 17’s delayed launch inserted into Earth orbit at 05:44, commencing the TLI burn procedures 3 hours later after two successful EPO passes. Figure 4.9.1-1.1 shows the charts with the orbital trajectories on them.

Figure 4.9.1-1.1: Earth Orbit charts (also known as APO charts). The one on the left is from this book, the December 6th date refers to what would have been the date in the USA had the mission taken off on time.

Figure 4.9.1-1.2  shows which parts of the Earth were in daylight at those times.

Figure 4.9.1-1.2: Daylight portions of the Earth at Earth Orbit Insertion (top) and Trans-Lunar Injection (bottom), derived here.

The reconstructed satellite image for the day is shown at the top of this page,and the source for the original document is in the introduction.

The scene is set, the task now is to look at the orbital images and place them on the map

The first shots are pretty easy as their locations are already known. AS17-148-22607,22608 and 22609 are in North Australia - two from the coast of the Gulf of Carpentaria, the other on the eastern shore of the Cape York Peninsula in northern Queensland (figure 4.9.1-1.3).

Figure 4.9.1-1.3: AS17-148-22607 (left) 22608 (centre) and 22609 (right).

Photos 22607 and 22608 are obviously of the same place, so let’s deal with those first. The Gulf of Carpenteria is the area between the two ‘prongs’ on the north Australian coast, and if you refer back to the EPO charts you’ll see it is clearly covered by the flight path. The photos were taken around an hour into the flight, as at 59 minutes we have this comment:

000:58:03 Cernan: Okay, we're looking at the deserts of Australia right now

At this point communications were being routed through Honeysuckle Creek, as noted by the PAO (Public Affairs Office). This page shows the times of Honeysuckle Creek’s involvement. In terms of where we are looking, the photographs are pretty much oriented in the direction of travel, and we can confirm their location by looking at Google Earth (see figure 4.9.1-1.4).

Figure 4.9.1-1.4: Google Earth (top row) and sections of AS17-148-22607 (bottom row). SkySafari depiction of location.

Coordinates are 17°19'6.28"S 134°27'23.18"E for the left and  15°51'47.01"S 136°33'48.65"E for the right.

The final photograph in the trilogy is looking almost vertically downwards, and we have confirmation of the time in this exchange:

001:00:33 Evans (onboard): Oh, look at the coral reef there, Geno.

               Cernan (onboard): Yes.

              Evans (onboard): Look at it; that's coral.

              Evans (onboard): Fantastic, Coral atolls.

The coral reef they are discussing is the Great Barrier Reef, and figure 4.1-1.5 shows a detail from the image compared with Google Earth.

The time stamp for the original comment (06:33 GMT) would put them a little short of the location required to take a vertical shot of the reef, hence my suggestion of a couple of minutes later - just enough time for someone to reach out for their camera and compose the shot.

The next sequence of photographs presents a more difficult challenge, in that there are no definite visual clues as to where they are. Figure 4.9.1–1.6 shows the triptych.

Figure 4.9.1-1.5: AS17-148-22609 detail (top left) compared with Google Earth (bottom left right). Coordinates  13°45'32.02"S 143°50'48.50"E. Top right is Google Earth indication of location, bottom right is SkySafari time depiction.

Figure 4.9.1-1.6: AS17-148-22610 (left), AS17-148-22611 (centre) and AS17-148-22612 (right)

We’re clearly looking at quite an impressive cloud feature, and at 1 hour 9 minutes we have the following:

001:08:56 Schmitt (onboard): There are some pretty lively looking clouds down there.

               Evans (onboard): Yes. Yes, yes.

               Schmitt (onboard): Better than [garble].

               Evans (onboard): Are we going right around the equator, must be.

               Cernan (onboard): Yes, we're - we're northwest of Samoa.

               Evans (onboard): [Garble] we went on a 91-degree [garble].

               Schmitt (onboard): There's a good-looking cloud for you; look at that one.

               Evans (onboard): Yes.

               Schmitt (onboard): Boy, you could snap a picture of that. [Chuckle.] I forget I got the darn camera.

               Schmitt (onboard): [Garble] be underexposed.

               Cernan (onboard): I can get that, Jack; give me that.

               Schmitt (onboard): I got it.

So, it sounds very like they are talking about this set of photographs.

As it happens there is quite a lively set of clouds along their flight path, shown below in figure 4.9.1-1.7.

Figure 4.9.1-1.7: Terminator position in SkySafari and the satellite image from launch day.

The position of the terminator shows that this lively looking cloud is pretty much on the terminator, and Schmitt (the crew’s resident meteorologist as well as geologist) does point out that:

 “In fact, it's a little low-pressure area, see it?”

shortly before the exchange given above.

That storm is approximately 1300 miles from the previous photograph, which must have been taken at about the point the crew were referring to seeing coral atolls. The speed recorded for them at this point is 17443 mph, or 290 miles a minute. The low pressure system identified on the satellite map is roughly 1550-1600 miles from the location of the previous photograph, so would have been taken at the most 6 minutes later.

Unfortunately there are no precise timings available for the Command Module audio transcriptions, and a lot depends on exactly how much time elapsed between seeing the coral reefs and them passing over them for the photograph.

That said, we know that around this time the crew experiences sunset, so it can’t be much further along their orbit, and the time gap between the two sets of photographs is about right. The tropical storm east of Papua therefore seems like a reasonable suggestion for the location of these three photographs.

The next image in the magazine (Figure 4.9.1-1.8) has very little to help us, and neither does the transcript).

Figure 4.9.1-1.8: AS17-148-22613

It’s pretty obvious that we are looking at either a sunrise or a sunset, and not one of the many references we get to an airglow or other lights on the horizon, eg:

001:33:47 Schmitt: Okay, I think we got the Gulf Coast showing up now by the band of lights, Bob.

We know from our maps that sunrise actually occurs over the mid-Atlantic. While they would see that sun approaching from some distance thanks to their elevated viewpoint, it would still be a while after that remark before it appeared.

There are quite a few exchanges once they cross the California coast that indicate that the cameras have been put down, or away, or misplaced - for example, some time around 001:23:00:

Schmitt (onboard): Guess what I've lost?

Cernan (onboard): What?

Schmitt (onboard): Camera.

The crew were also quite busy as the cross the USA with the various check-out procedures they needed to complete before TLI, but despite that the only possible angle they can use to take the photograph is forwards, so it must be of the approaching sunrise.

We can be a little more definite about the next sequence of images, given that they start with an obvious only just daylight area of ocean and end, quite definitely, in the African coastline (more about this later).

The first three in the sequence are shown in figure 4.9.1-1.9.

Figure 4.9.1-1.9: AS17-148-22614 (left), AS17-148-22615 (centre) and AS17-148-22616 (right)

We can tell that these are sunrise images mostly from the slightly darker left hand edge of the first two photographs, but mostly from the hugely elongated shadows of the clouds nearer the horizon.

We also have a couple of references in the transcript that allow us to position the photographs. Here we have Schmitt giving us a precise reference point:

001:38:43 Schmitt: Looks like we're right over the Bahamas now, Bob.

Which at this point would still be darkness. We then have the crew losing direct communications with Houston, transferring first to the airborne ARIA system and then Ascension island at 001:51.

17 minutes later we have:

001:55:26 Schmitt: Okay, Bob. We had - as usual - up here [laughter] a spectacular sunrise

Figure 4.9.1-1.10 shows the relative position of the terminator, the Apollo spacecraft and the location, and receiving capability, of the Ascension Island tracking station.

Figure 4.9.1-1.10: SkySafari terminator position (above) and the location and receiving capability of Ascension Island tracking station (Source).

The evidence of these two maps should put us fairly and squarely between South America and Africa.

We also have the following descriptions by Schmitt

001:56:20 Schmitt: Bob, we're over - what might be - intermediate to low stratus that have a very strong crenulation pattern

and

001:56:38 Schmitt: Looks like about a north-south lineation with a very strong crinkling, roughly east-west.

which seem to match what he’s describing.

For the third image in this sequence we can bring in a view from one of the post-TLI images. It’s obviously looking towards the rising sun, and when the contrast and brightness are enhanced we can see north-south trending lines of clouds, with some decent looking thunderheads casting long shadows and a decent sized cloud mass in the north. If we compare that view with that from AS17-148-22680 (figure 4.9.1-1.11) we can find an area over near the horizon, just after where the terminator would be and south of Saharan Africa. In just the right spot, in other words.    

The green arrow gives a rough approximation of the EPO flight path, and this is a great help in identifying the location of the next two images.

Finding the location of these two (AS17-148-22617 and AS17-148-22618) again requires a little detective work, and being able to locate a later photograph more precisely. That later image is the next in the sequence, AS17-148-22619, which is shown below in figure 4.9.1-1.12.

Figure 4.9.1-1.11: AS148-22680 with a section highlighted (right) matching AS17-148-22616.

The picture shows an area of thicker cloud viewed looking down and slightly across.The EPO photograph has an area in the post-TLI that very closely matches it that just happens to be right below where Apollo 17 was passing. It’s not an exact match, but why would it be given that the two photographs were taken a couple of hours apart?!

We also have an excellent description of what we’re seeing in the transcript, with Schmitt saying:

001:58:26 Schmitt: Well, I certainly am, Bob, and - again there's a big - a fairly continuous intermediate cloud deck, I think. And it has patterns comparable to what I've seen on pictures of ice floes.

001:58:40 Overmyer: Roger. Understand.

001:58:40 Schmitt: And - of pack ice; I should say pictures of pack ice in the Antarctic.

An extremely accurate description! Schmitt also waxes lyrical on his website about the view:

“New patterns suddenly jump into view. Over the South Atlantic, between Africa and South America, a solid layer of morning clouds lies crenulated from one horizon to the other like an old washboard. Jagged breaks in those wrinkled strata give the illusion of polar pack ice fracturing and moving apart.”

We now know where this image was taken, and we know what sort of area we need to be looking at, can this help us track down the images taken between sunrise and this one?

Well, we know the trajectory of the EPO, and we also know where Apollo 17 passes over Africa, which allows us to plot which parts of the Atlantic they crossed on the way to that point (see the EPO trajectory in figure 4.9.1-1.10). The size of the area covered in figure 4.9.1.11 also helps us determine the size of the search area. Knowing these facts allows us to determine that the previous two photographs are of an area a little north of the ‘ice flow’ (figure 4.9.1-1.13).

Figure 4.9.1-1.12: AS17-148-22680 (left), AS17-148-22619 (centre) and the same area in AS17-148-22680 (right)

Figure 4.9.1-1.13: AS17-148-22617 (left), AS17-148-22618 (right) and their locations on AS17-148-22680 (below left. SkySafari time depiction is set at the time of Schmitt’s comments

In the figure above the green box shows the cloud bank in 22617, yellow 22618, and the red box is a reminder of the location of AS17-148-22619. The time stamp for Schmitt’s comments put them in exactly the right place, and the EPO photographs are a clear match for the post-TLI ones taken a while later..

Finding the location of the next image isn’t too difficult, as the information you need is also in the one we’ve just looked at. Figure 4.9.1-1.14 shows AS17-148-22621 and compares it with an area visible in AS17-148-22620.

Figure 4.9.1-1.14: AS17-148-22620 (left), its location on AS17-148-22619 and suggested location on AS17-148-22682.

Figure 4.9.1-1.15: AS17-148-22621 above) compared with a section of AS17-148-22679 (above right), and with a section elongated to compensate for curvature (right).

Can we be sure we’ve got the correct place? Nothing is ever certain but if we look closely at the image we can see that its right hand edge there is much more open water, and the gaps between cloud masses are becoming wider. To the north we have a boundary of thinner cloud, and this seems to be what we have around the area I’ve outlined. I think we can be reasonably confident that we have located another photograph in this sequence.

The next one is again looking towards the east, and we can help in our identification process by stretching the area at the eastern limb to make it look more like the view from above (see figure 4.9.1-1.15).

Again, allowing for a couple of hour’s time to elapse and changes in perspective we have a very good match for the location of this final trans-oceanic image. Once this photograph is out of the way we start to get recognisable features as the mission hits the African coast. Figure 4.9.1-1.16 shows the collection of coastal images.

Figure 4.9.1-1.16: (top row left to right) AS17-148-22622, AS17-148-22623, AS17-148-22624, AS17-148-22625. Bottom row: merged image of those on the top row (left) Google Earth with superimposed AS17-148-22626 (centre), AS17-148-22626 (centre right), Section of satellite image (bottom right). SkySafari time estimate right.

There isn’t much we can add here as it’s pretty obvious that Apollo 17 took these images as they passed over the coast at the Angola-Namibia border, taking some great shots of Baia dos Tigres on the way. SkySafari tells us that this would have been at around 07:36 GMT.

After crossing into African airspace they continue to take photographs, some looking almost straight down, others at an oblique angle, mostly looking towards the north or in the direction of travel. Figure 4.9.1-1.17 shows the location of those photographs, with the approximate centre point of oblique images shown by the yellow markers.

There’s not much to say about these as it’s pretty obvious that the mission is following the well defined EPO path across Africa just as the charts show, but what we can do is show what the oblique images are looking at (figure 4.9.1-1.18a-d).

Figure 4.9.1-1.17: Location of Apollo 17’s trans-African photography

Figure 4.9.1-1.18b: AS17-148-22629-30 to AS17-148-22633-35 over the Okavango Delta and surrounds, together with Google Earth photograph locations and SkySafari time depiction.

Figure 4.9.1-1.18a: AS17-148-22627 and AS17-148-22628 looking at the Etosha Pan (left) and Bicuar & Mupa national parks (right). Far right is SkySafari suggestion of time for the photographs

Figure 4.9.1-1.18c: AS17-148-22636 - AS17-148-22640 showing the Ntwetwe and Sua pans (left) and the Botswana, Zimbabwe and South African border area on the way to the Mozambique coastal port of Maputo. Also shown is a Landsat tile covering the same are as AS17-148-22640

Figure 4.9.1-1.18d: AS17-148-22641 - AS17-22645 showing the Limpopo river and Mozambique coast

The existence of a Landsat tile covering the same weather system visible in the above is an added bonus, and there’s more on that image in the post-TLI section of day 1. The same band of cloud can be seen covering the same area heading towards the coast, almost as if the were there to witness it! The Landsat tile was imaged at 07:19 on the 7th, compared with a time of around 07:40 for the Apollo one. There isn’t any kind of commentary recorded while crossing Africa, and the next stop for our planetary photographs is Madagascar (figure 4.9.1-1.19).

Figure 4.9.1-1.19: Merged photo using AS17-148-22646-7 (left), AS17-148-22650 (top centre), AS17-148-22649 (bottom centre), NOAA-2 view of Madagascar (top right) and Google Earth view showing approximate location of  AS17-148-22646-50 (bottom right).

So far so good, and again we have the added bonus of the clouds visible in the EPO photographs also being shown in the satellite imagery from the day of launch.

As with Africa, Madagascar is beautifully clear, as the crew relay to their next point of contact in Australia:

02:28:32 Schmitt: Okay. You've got Omni Charlie. And, Bob, we had almost a completely weather-free pass over Africa and Madagascar. And the scenery - both aesthetically and geologically - was something like I've never seen before, for sure.

002:28:56 Overmyer: Roger.

002:28:59 Schmitt: We got odds and ends on the tape and quite a bit on the film.

002:29:04 Overmyer: Roger; good show. Are you saying that you didn't have any weather over that southern Africa there?

002:29:10 Schmitt: Not very much. Barely broken clouds in some places. Most of the countryside was clear.

The clouds over the high ground on the island are also visibly in the Apollo photograph.

The next two images present more of a problem, as again we are faced with photographs that have no apparent land masses visible, and no transcript record available to help us. Figure 4.9.1-1.20 shows the pair.

The second view in particular is one taken at a near vertical angle, so we can deduce that it covers a relatively small area. That said, we can see a small amount of the horizon’s curve. What we can also notice below some of the higher altitude cirrus clouds is a shadow cast on the ocean below, and the angle of that shadow is comparable to the angle of the shadows cast by clouds in the preceding photographs (not to be confused with patterns on the landscape).

The conclusion I draw from this is that these two images were taken at around the same time and location. Are there any clouds we can identify in the post-TLI images? Let’s look at one in figure 4.9.1-1.21.

Figure 4.9.1-1.20: AS17-148-22651 and  AS17-148-22652

Can I be absolutely certain that I have the right area? No. Can I be specific about which group of clouds in that area is the one photographed in EPO? No? Is it consistent with where Apollo 17 was at a time when photographs were being taken? Absolutely yes. It’s south-east of Madagascar at the right position for their EPO pass and shows an area populated with twin bands of thicker cloud crossed by lighter high cloud and clear ocean around it.

Leaving that whacking great set of assumptions behind we can now move on to the next set of images. Some of these are easier to locate than others and we sometimes have to delve deep behind the clouds to find their locations. Figure 4.9.1-1.21 shows the first in this series.

Figure 4.9.1-1.21: AS17-148-22685 with suggested location of AS17-148-22651 and  AS17-148-22652, and a zoomed crop of that area.

Figure 4.9.1-1.21: AS17-148-22653 and AS17-148-22654

At first glance we have very little to go on, however if we look carefully halfway down the right hand side of the image we see this (figure 4.9.1-1.22).

Where in the world could this be?

A bit of scouting around on the flight path finds that what we are looking at is the western end of the Indonesian island of Pulau Wetar. It’s shown in close up and in context in figure 4.9.1-1.23 together with an image taken from orbit by a Space Shuttle mission.

Figure 4.9.1-1.22: Close up of AS17-48-22653

Figure 4.9.1.1-23: Google Earth views showing the location of the photos in figure 4.9.1-1.22, together with a Space Shuttle image of Pulau Wetar and SkySafari time estimate

The orientation of the island shows that this view is towards the north from a position below Timor, which is underneath the long bank of cloud across the centre of the photograph. At this point in the orbit they will have just passed out of contact with Carnarvon on Australia’s west coast but are sill out of range of the next tracking station and are waiting to be picked up by Hawaii. As in the previous gap between tracking stations we have no record of what was said by the crew, and for the location of the next photograph we have to skip onwards to two photographs taken after it. These three photographs are shown in figure 4.9.1-1.24.

Figure 4.9.1-1.24: AS17-148-22655, AS17-148-22656 and AS17-148-22657

As with the previous apparently oceanic images we have little to go on, but once again if we zoom in closely we can find a useful detail (figure 4.9.1-1.25).

We now have a confirmed location for the 2 pairs of photographs either side of AS17-148-22655, can we provide a definite location for it?

In a word, no.

We can, however, look at a few indications as to where it might be. One obvious indicator of the orientation of the photograph is in the bottom left corner, where the shadows of the taller more prominent clouds are long. It’s heading towards sunset in this part of the world, and the sun is behind them over the Indian ocean, so we can be certain that we are a still looking roughly in the direction of travel. The presence of the CSM window on the right hand side also suggests a slight change of the viewing angle to the right of the images that followed.

If that is the case then we ought to be able to see some sort of land mass somewhere. Figure 4.9.1-1.26 shows a close up of the horizon in AS17-148-22655.

Figure 4.9.1-1.26: Close up of sections of the horizon in AS17-148-22655.

Figure 4.9.1-1.25: Section of AS17-148-22656 compared with the same area on Google Earth.

While it isn’t possible to identify with any certainty at all exactly which land mass we are looking at, we can say that we are looking at a land mass, and the only land mass of any significant size in the direction in which they are travelling and from this position is Papua New Guinea. The photo might also help us to identify the location of what comes next, more of which shortly.

The last set of images in the sequence before the post-TLI photographs, are AS17-148-22658 to AS17-148-22668. The final 3 photgraphs are of a bright horizon but otherwise in the dark, so we are either looking at airglow (which they do mention seeing) or backwards at the sunset. We’ve already established where the last two photographs were taken, we know where Apollo 17 was heading, and we also know that before long they will be passing into darkness. Figure 4.9.1-1.27 illustrates the point.

Figure 4.9.1-1.27: Left is a Celestia projection of the Earth at the time of the last orbit around the terminator. The red circles mark the last positively identifiable photograph locations and the red arrow the approximate path of the EPO. The arrowhead marks the terminator. Right is a SkySafari depiction of the orbital path.

We have, therefore, a relatively narrow window in which the final photographs were taken. However, we know where they were going and have a pretty good idea of exactly which path they were following, so we now need to see if we can identify where the following three photographs are showing (figure 4.9.1-1.28).

Figure 4.9.1-1.28: AS17-148-22658, AS17-148-22659 and AS17-148-22660

The angle of this cloud, the change in direction of the horizon and the direction of the shadows are all suggestive of  the camera looking further to the right than the images showing Pulau Adi. The pattern of the clouds are also suggestive of covering a mountainous land mass and then breaking up along the coastline in the distance. The sequence of the images also shows that they are taken along the EPO flight path, given that the final image is taken looking straight down over the cloud mass in the centre of the photographs taken immediately before it. The last photograph also seems to show dark land where any gaps in the cloud can be seen.

Figure 4.9.1-1.29 illustrates the view along that flight path over the Sudimar Range and Moake Mountains, and the satellite view confirming the presence of the clouds we’re seeing.

Figure 4.9.1-1.29: EPO flight path over Papua New Guinea, as derived from the EPO map superimposed on Google Earth, and satellite view of the same area.

As hinted at earlier there are also possible clues in AS17-148-22655 (figure 4.9.1-1.30).

Figure 4.9.1-1.30: Section of AS17-148-22655 (left) to show the location of the zoomed area (top left), compared with the cloud mass shown in AS17-148-22660 (top right).

As usual, we have to add the caveat that other cloud masses are available, but it is in the right place, and has the right morphology, so it seems a reasonable conclusion to draw.

Now on to the final images, taken as they approach the terminator and prepare for the TLI burn (figure 4.9.1-1.31).

Figure 4.9.1-1.31: Left to right - AS17-148-22661, AS17-148-22662, AS17-148-22663, AS17-148-22664, AS17-148-22665

We have the same issue here as we have had with previous photographs in that we have no land mass on which we can pin with any certainty. However if we assume that the last photograph examined is directly over the high peaks of Papua New Guinea and we are continuing to take images in the direction of travel, then we can safely assume that we are looking at the last section of open ocean before the sunset. The angle has changed again, suggesting we are looking slightly north of East than the last images that were slightly south of it.

We can determine that the first image does contain the location of the other 3. Figure 4.9.1-1.32 shows that we can follow the progress of the crew towards the terminator. While it’s relatively easy to find the areas in the first 4 photographs, the last one is slightly trickier, and I’ve used an area of cloud on the horizon to confirm it.

Figure 4.9.1-1.32: Above - Montage of 4 of the images shown in figure 4.12.38 (AS17-148-22664 is only marginally different to AS17-148-22663 and is omitted), with a red outline identifying the location of the next image in the sequence. Right, stretched section of AS17-148-22663 compared with the same area in AS17-148-22665

The next question then, again, is ‘can we identify where this is’?

Again, in a word, no, but we can see if there are any areas in other photographs that look similar. Figure 4.9.1-1.33 shows AS17-148-22660 with an area identified. That area has been stretched to try and make it cover the same sort of area as AS17-148-22661.

Figure 4.9.1-1.33: Zoomed and stretched section of AS17-148-22660.

The main reasons for picking out this area are that firstly it lies in the path of Apollo 17, and secondly the presence of the shadow line under the band of cloud running across the photo, together an obvious gap in that cloud and an area of more broken cloud before that.

Conclusive? No. Reasonable? Yes.

We’ve now, admittedly with some conjecture and guesswork, identified the locations of all the photographs taken while Apollo 17 was in EPO. The final three photographs before we start to see images that are definitely post-TLI are shown in figure 4.9.1-1.33.

Figure 4.9.1-1.34: AS17-148-22666, AS17-148-22667 and AS17-148-22668

They are obviously of the approaching sun, and Cernan mentions that TLI would take them through sunrise.

That’s it, all done. We now have a complete map of where images were taken, and for the tl:dr generation, here it is summarised on the map (figure 4.9.1-1.35).

That’s it for EPO. Once around the block they fire up the engines and head for the moon, at least part of which is covered in the second part of launch day. Click the link below.

Figure 4.9.1-1.35: Suggested locations of Apollo 17 EPO images.