Users of the image products are referred to the following links, which highlight examples of anomalies and features found in the WISE imaging data.
Note: There is a similar set of image anomalies and features for single-exposure images in II.4.b.ii.
Each figure below shows two rows of images. From left to right in the top row are shown the full Atlas images for W1, W2, W3, W4, and a three-color image comprised of W1(blue) + W2(green) + W3(red). From left to right in the bottom row are the coverage maps for W1, W2, W3, and W4, and a three-color image of the full Atlas images shown in the top row, comprised of W2(blue) + W3(green) + W4(red). The greyscale stretch in the coverage maps goes from black for a coverage of four or fewer frames up to white for the maximum coverage in the image. This maximum coverage value can vary depending on factors such as ecliptic latitude and the quality scores of the input frames.
Click on the thumbnails to see the images at higher resolution. Readers are encouraged to use the WISE image service at IRSA to preview these same images and to download the FITS files for further study. To aid the reader, values of the coadd_ID are provided in the caption of each image set below.
Image examples below are divided into the following categories:
Anomalies: Anomalies originate from the behavior of the arrays themselves and are not astrophysical.
Latents: Normal (single-epoch) latents
Figure 1 - Atlas image 1034m485_ab41. Latents from bright stars coadd constructively for framesets in which the star is observed in the same scan direction because its latent sources fall at or very near the same point on the sky (unless the star is near the ecliptic poles). In this example, the two bright stars near the center of the image create a trail of latents extending up and slightly to the left. |
Figure 2 - Atlas image 0305p075_ab41. Latents from bright stars coadd constructively for framesets in which the star is observed in the same scan direction because its latent sources fall at or very near the same point on the sky (unless the star is near the ecliptic poles). In this example, an extremely bright star with WISE data spanning epochs six months apart leaves a trail of W3- and W4-bright latents on opposite sides of the star. At one epoch the star was observed in north-going scans, and at another epoch it was observed in south-going scans. |
Figure 3 - Atlas image 0347m031_ab41. Latents from bright stars coadd constructively for framesets in which the star is observed in the same scan direction because its latent sources fall at or very near the same point on the sky (unless the star is near the ecliptic poles). In this example, the extremely bright star omicron Ceti (Mira) leaves a trail of W3- and W4-bright latents, ghost images, and latents from the ghosts themselves. |
Figure 4 - Atlas image 0587p121_ab41. Latents from bright stars coadd constructively for framesets in which the star is observed in the same scan direction because its latent sources fall at or very near the same point on the sky (unless the star is near the ecliptic poles). In this example a trail of decaying latents is seen running from the bright star toward the upper right corner of the image. |
Latents: Smeared latents from twist near the ecliptic poles
Figure 5 - Atlas image 1002m667_ab41. Latents from bright stars coadd constructively for framesets in which the star is observed in the same scan direction because its latent sources fall at or very near the same point on the sky (unless the star is near the ecliptic poles, as in this example). Here, a bright star off the right side of the image leaves a W3/W4 latent that is elongated in the final coadds. Because the change in scan angle from earliest to latest frame is still small, outlier rejection during the coaddition process does not completely remove the latent signature. |
Figure 6 - Atlas image 0943m652_ab41. Latents from bright stars coadd constructively for framesets in which the star is observed in the same scan direction because its latent sources fall at or very near the same point on the sky (unless the star is near the ecliptic poles, as in this example). Here, the bright star in the lower right corner leaves a W3/W4 ghost and latent that are arc-shaped in the final coadds. Because the change in scan angle between consecutive frames is small, outlier rejection during the coaddition process does not completely remove the latent signature. |
Figure 7 - Atlas image 2709p666_ab41. Latents from bright stars coadd constructively for framesets in which the star is observed in the same scan direction because its latent sources fall at or very near the same point on the sky (unless the star is near the ecliptic poles, as in this example). Here, the bright planetary known as the Cat's Eye Nebula (NGC 6543), which is located less than 0.2 deg from the north ecliptic pole, is seen at the right side of the image. The W3/W4-bright nebula leaves a sweeping W3/W4 artifact that forms a semi-circle in the final coadds. Outlier rejection during the coaddition process has removed the brightest parts of the latent signature, but the low-level structure is not completely removed and results in the large arc seen here. |
Latents: Smeared latents from moving objects
Other bright star effects: Reflection artifacts
Figure 9 - Atlas image 0720m606_ab41. The diffuse glow across this image is caused by constructive coaddition of "half-frame" glows from the bright star R Doradus, just off the field. |
Figure 10 - Atlas image 0408m546_ab41. The bright star in this image produces a glint artifact trailing off to the lower left in the final coadd. |
Electronic artifacts: Diagonal striping pattern
Figure 11 - Atlas image 0000m576_ab41. Electronic noise can sometimes coadd constructively to produce effects such as the faint banding pattern seen here at W2. |
Features: Features are caused by real, astrophysical objects or poor coverage and may look like anomalies.
Low coverage: Holes in the images
Low coverage: Frame-level NaNs
Low coverage: "Tiger-claw scratches" caused by planet diffraction spikes
Figure 14 - Atlas image 1348p181_ab41. Outlier rejection is unable to remove single-frame anomalies if they are not significantly deviant from the values of surrounding pixels. In the example shown here, diffraction spikes from Mars, which marched slowly across the top of the field as the WISE data were taken, were imprinted into the W3 and W4 images as a series of parallel streaks. (For an explanation of the non-uniform backgrounds in W3 and W4, see Figure 15.) |
Odd patterns: Variable cirrus, changing zodiacal backgrounds, and scattered Moonlight
Odd patterns: Bleed-through of satellite trails
Figure 16 - Atlas image 0512m197_ab41. Fainter, one-frame-only events such as the passage of a satellite during scan mirror fly-back will not trigger outlier rejection during the coadd generation step. In such cases, as with the latent from a kinked satellite trail seen in W3 and W4 at upper left, these one-time-only events may imprint into the Atlas images. |
Odd patterns: Doughnut-shaped artifact left by space debris
Slowly moving sources: "Blob" caused by planet
Slowly moving sources: "Blob" caused by comet
Slowly moving sources: Streaks caused by asteroid
Real sources: Comet debris trails
Figure 22 - Atlas image 2028m076_ab41. Comet debris trails will also be seen in the images since these appear in single-exposure images. These may smear out slightly in the Atlas images because of parallax: WISE's Earth-based vantage point changes slightly from frame to frame because these objects are very nearby. (The bright star also leaves two-epoch latents as described in Figure 2.) |
Real sources: Bubbles and shells
Figure 23 - Atlas image 1677m652_ab41. Bubbles and shells seen in the single-exposure frames will, of course, also appear in the Atlas images and may mimic an artifact. In this example a W4-bright shell around the Wolf-Rayet star WR40 is seen. |
Figure 24 - Atlas image 0066p636_ab41. Bubbles and shells seen in the single-exposure frames will, of course, also appear in the Atlas images and may mimic an artifact. In this example the W4-bright Tyhco supernova remnant is seen. |
Last update: 2012 January 31