<table><caption>**Table C.2.** Data products produced for SC8 pilot phase field production.</caption><thead><tr><th>Channel</th><th>Image type</th><th>Original number of images</th><th>Number of productions</th><th>Final number of images</th><th>Number of products per image</th><th>Number of products</th><th>Storage (GB)</th></tr></thead><tbody><tr><td>VIS</td><td>Science Wide</td><td>16</td><td>12</td><td>192</td><td>1</td><td>192</td><td>1294</td></tr><tr><td>VIS</td><td>Bias</td><td>60</td><td>1</td><td>60</td><td>1</td><td>60</td><td>404</td></tr><tr><td>VIS</td><td>Flat</td><td>60</td><td>1</td><td>60</td><td>1</td><td>60</td><td>404</td></tr><tr><td>NISP-P</td><td>Science Wide</td><td>48</td><td>14</td><td>672</td><td>1</td><td>672</td><td>263</td></tr><tr><td>NISP-P</td><td>Dark</td><td>600</td><td>1</td><td>600</td><td>1</td><td>600</td><td>234</td></tr><tr><td>NISP-P</td><td>Flat</td><td>750</td><td>1</td><td>750</td><td>1</td><td>750</td><td>293</td></tr><tr><td>NISP-P</td><td>Self Cal</td><td>180</td><td>1</td><td>180</td><td>1</td><td>180</td><td>70</td></tr><tr><td>NISP-P</td><td>Std Stars</td><td>24</td><td>1</td><td>24</td><td>1</td><td>24</td><td>9</td></tr><tr><td>NISP-S</td><td>Science Wide</td><td>16</td><td>6</td><td>96</td><td>1</td><td>96</td><td>375</td></tr><tr><td>NISP-S</td><td>Std Stars</td><td>8</td><td>1</td><td>8</td><td>1</td><td>8</td><td>32</td></tr><tr><td>NISP-S</td><td>PN</td><td>16</td><td>1</td><td>16</td><td>1</td><td>16</td><td>62</td></tr><tr><td>DES</td><td>Science Wide</td><td>76</td><td>5</td><td>380</td><td>1</td><td>380</td><td>408</td></tr><tr><td>DES</td><td>Flat</td><td>40</td><td>1</td><td>40</td><td>1</td><td>40</td><td>43</td></tr><tr><td>DES</td><td>Bias</td><td>10</td><td>1</td><td>10</td><td>1</td><td>10</td><td>11</td></tr><tr><td>LSST</td><td>Science Wide</td><td>65</td><td>4</td><td>260</td><td>189</td><td>49 140</td><td>3004</td></tr><tr><td>CFIS</td><td>Science Wide</td><td>14</td><td>4</td><td>56</td><td>40</td><td>2240</td><td>30</td></tr><tr><td>JEDIS</td><td>Science Wide</td><td>23</td><td>3</td><td>69</td><td>14</td><td>966</td><td>138</td></tr><tr><td>Pan-STARRS</td><td>Science Wide</td><td>40</td><td>3</td><td>120</td><td>60</td><td>7200</td><td>221</td></tr><tr><td>WISHES</td><td>Science Wide</td><td>7</td><td>3</td><td>21</td><td>103</td><td>2163</td><td>23</td></tr></tbody></table>

Notes. The calibration frames were reused from previous challenges.

validate the OU-VIS processing and analysis software. Thus, while the pilot phase area only included four *Euclid* observations overlapping one *Euclid* tile and a small sample of EXT pointings per band, multiple productions were launched with each new release due to new and/or modified features. In Table C.2, we list all products produced for a given instrument channel during the pilot phase, noting the number of images per production, number of production sequences and the final number of products and storage requirements. For the *Euclid* instruments, as each observation has 4 dithers a total of 16 images were to be simulated for VIS, 48 images for NISP-P, and 16 images for NISP-S for the pilot phase production. However, we performed 12, 14, and 6 productions, respectively for VIS, NISP-P, and NISP-S channels yielding 192, 672, and 96 data products. As seen in Table C.2, multiple productions were also carried out for each EXT survey. A total of 3,614 exposures were produced during the pilot phase. Furthermore, for Rubin and the Northern Surveys, each simulated detector frame comprising an image was saved as an individual file. Thus, the total number of data products ingested into the EAS was 64,679 amounting to 7.1 TB.

For each production sequence, we characterised the resources needed for each processing element (i.e. memory, CPU, processing time, and storage). This was to assess whether the resources originally requested to the HTC systems at each SDC for each payload job would suffice for the SC8 Main run. In Table C.3, we report the final profiling results of the main processing elements of the SIM pipeline described in Sect. 5 for each instrument.

We used the upper-bounds reported to issue a request for resources to the HTC system, which had to be sufficiently higher than the observed maximum but somewhat conservative to optimise SDC performance and capacity. Table C.4 lists the resource characterisations for each software release and the configuration of each processing element used to produce image simulations for the SC8 main run.

<table><caption>**Table C.3.** Detector frame simulation resources.</caption><thead><tr><th rowspan="2">job</th><th colspan="2">wall time (h:mm)</th><th colspan="2">RSS (GB)</th><th colspan="2">VMEM (GB)</th></tr><tr><th>avg</th><th>max</th><th>avg</th><th>max</th><th>avg</th><th>max</th></tr></thead><tbody><tr><td>VIS detector</td><td>2:37</td><td>4:49</td><td>2.8</td><td>5.9</td><td>11.2</td><td>14.6</td></tr><tr><td>NISP-P detector</td><td>0:34</td><td>1:14</td><td>4.3</td><td>5.9</td><td>4.8</td><td>6.6</td></tr><tr><td>NISP-S detector</td><td>5:21</td><td>8:40</td><td>1.1</td><td>7.2</td><td>1.3</td><td>13.5</td></tr><tr><td>SIM_EXT detector</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>DES</td><td>0:06</td><td>0:16</td><td>0.5</td><td>1.0</td><td>0.8</td><td>1.4</td></tr><tr><td>LSST</td><td>0:34</td><td>1:50</td><td>0.3</td><td>3.8</td><td>0.5</td><td>6.5</td></tr><tr><td>CFIS</td><td>0:03</td><td>0:15</td><td>0.6</td><td>1.6</td><td>1.1</td><td>2.2</td></tr><tr><td>JEDIS</td><td>0:16</td><td>0:49</td><td>1.2</td><td>1.8</td><td>1.5</td><td>2.2</td></tr><tr><td>Pan-STARRS</td><td>0:08</td><td>1:18</td><td>0.6</td><td>1.4</td><td>0.9</td><td>2.0</td></tr><tr><td>WISHES</td><td>0:03</td><td>0:12</td><td>0.7</td><td>1.9</td><td>1.2</td><td>2.6</td></tr><tr><td>NS Afterburner</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>CFIS</td><td>0:01</td><td>0:01</td><td>0.6</td><td>0.9</td><td>1.9</td><td>3.8</td></tr><tr><td>JEDIS</td><td>0:09</td><td>0:23</td><td>4.9</td><td>6.9</td><td>5.8</td><td>7.4</td></tr><tr><td>Pan-STARRS</td><td>0:05</td><td>0:58</td><td>1.4</td><td>2.0</td><td>2.1</td><td>5.3</td></tr><tr><td>WISHES</td><td>0:00</td><td>0:02</td><td>0.6</td><td>0.8</td><td>1.2</td><td>4.8</td></tr></tbody></table>

Notes. Resources required to simulate a given detector frame using the corresponding simulator, observed during SC8 pilot phase: Wall time, Resident Set Size (RSS), and Virtual Memory (VMEM).

## Appendix C.4. SC8 main survey files

The SC8 main area was reduced from a continuous region measuring 600 deg² to 11 patches with a total area of approximately 165 deg². Figure C.3 shows the distribution of *Euclid* observations among 11 discontiguous regions. For the EXT surveys, we subdivided the original SC8 main area into three non-overlapping patches. The area above 30° in Declination was covered by the Northern Surveys in certain broadbands: CFIS (u and r bands), JEDIS (g band), Pan-STARRS (i band), and WISHES (z band). The rectangular region below 30° in Declination was further sub-divided into two sections along a diagonal
<table><caption>**Table C.4.** Program and version used for each of the main jobs in the SIM pipeline and resources requested to run on an HTC system</caption><thead><tr><th>job</th><th>project</th><th>version</th><th>n cpu</th><th>RSS (GB)</th><th>wall time (h)</th></tr></thead><tbody><tr><td>VIS detector</td><td>ELViS</td><td>1.20.3</td><td>1</td><td>8</td><td>6</td></tr><tr><td>NISP-P detector</td><td>SIM_Imagem</td><td>1.9.11</td><td>1</td><td>8</td><td>10</td></tr><tr><td>NISP-S detector</td><td>SIM_TIPS_Simulator</td><td>5.4.4</td><td>1</td><td>4</td><td>50</td></tr><tr><td>SIM_EXT detector</td><td>SIM_EXT</td><td>2.14.2</td><td>1</td><td>4</td><td>6</td></tr><tr><td>NS Afterburner</td><td>EXT_NS_AFTERBURNER</td><td>2.0.0</td><td>1</td><td>8</td><td>2</td></tr></tbody></table>

to allow a range of sky conditions in both segments. The area above the diagonal contained the set of Rubin pointings for each broadband filter (e.g. *u*, *g*, *r*, *i*, and *z* bands), whereas the region below the diagonal contained only DES pointings for the bands (*g*, *r*, *i*, and *z* bands). OU-EXT provided a set of files containing the respective observing cadence strategies for each survey from which we selected exposures that intersect the SC8 main area for processing. The preparation of each survey file is described below and their corresponding file contents are summarised in Table C.5:

- **CFIS** The pointings from the available CFIS data for SC8 preparation did not cover the whole SC8 area of the sky. Therefore, the pointing pattern from another area of the sky with similar declination was translated to the SC8 area as shown in Figure C.4.

- **JEDIS** By the start of SC8, JEDIS observations had yet to be performed. The pointing pattern was generated following procedures outlined by the JEDIS team. For any given sky location, the pattern consists of 14 overlapping pointings with a dithering step of the size of the JEDIS CCD, so that each point in the sky is imaged with all the 14 CCDs of the camera. The JEDIS SC8 footprint and depth in layer count can be seen in Figure C.5.

- **Pan-STARRS** A pre-selection of all pointings overlapping the SC8 area was performed by OU-EXT. They reduced the original number of pointings to 6.5 times of the total in order to minimise data storage. To reach the required depths, the exposure times were increased from 240.0 s to 292.5 s. The saturation limit of the CCDs was increased accordingly in order to retain the saturation limit of the stars. Figure C.6 shows the Pan-STARRS PS1 SC8 footprint and the depth indicated by the contours denoting the layer count.

- **WISHES** The survey file in the *z* band was built from real WISHES pointings overlaying the SC8 area (as seen in Figure C.7 which includes the corresponding number of layers).

- **Rubin** The LSST scheduler (Naghib et al. 2019) and associated simulated pointing histories (OpSim outputs) provide many examples of survey strategy options (Delgado & Reuter 2016; Connolly et al. 2014). For this work, a survey table was derived courtesy of the Dark Energy Science Collaboration (DESC) using the wide-fast-deep output from the v1.5 simulation, footprint_sky_dustv1.5_10yrs (Jones et al. 2020), which we downsampled in order to reach the desired limiting magnitudes in *ugriz* for the Euclid Wide Survey. We show in Figures C.8 and C.9, respectively, the number of layers in the *u* and *g* bands for the Rubin SC8 main survey. Magnitude zero points estimates for each bandpass were provided by DESC. Furthermore, the same position angle was used for all visits; therefore, we did not account for rotation of the camera denoted by the OpSim parameter 'rottelpos'.

- **DES** Similar to CFIS, the SC8 region is also outside of the DES footprint, observations were extracted from the same

range of Declination in the southern celestial hemisphere at a shifted Right Ascension and transformed to cover the SC8 area. An additional margin of 1.05 deg, half of DECam FOV, (Flaugher et al. 2015), was applied to the selection to ensure that all exposures overlapping the target area were included. Fig. C.10 shows the resulting DES SC8 footprint and the blue contours indicate the number of layers to reach the desired depth for bands *griz*.

<table><caption>**Table C.5.** Number of exposures selected for processing and average number of layers in SC8 main area for each of the survey-band pairs</caption><thead><tr><th>Survey</th><th>Bands</th><th>Num exposures</th><th>Num layers</th></tr></thead><tbody><tr><td><em>Euclid</em></td><td><em>I</em><sub>E</sub>, <em>J</em><sub>E</sub>, <em>H</em><sub>E</sub>, <em>Y</em><sub>E</sub>, and Spectro</td><td>331</td><td>4</td></tr><tr><td><em>DES</em></td><td><em>g</em>, <em>r</em>, <em>i</em>, <em>z</em></td><td>593</td><td>10–15</td></tr><tr><td rowspan="5"><em>LSST</em></td><td><em>u</em></td><td>201</td><td>10–15</td></tr><tr><td><em>g</em></td><td>133</td><td>5–10</td></tr><tr><td><em>r</em></td><td>130</td><td>5–10</td></tr><tr><td><em>i</em></td><td>139</td><td>5–10</td></tr><tr><td><em>z</em></td><td>197</td><td>10–15</td></tr><tr><td><em>CFIS</em></td><td><em>u</em>, <em>r</em></td><td>673</td><td>~ 4</td></tr><tr><td><em>JEDIS</em></td><td><em>g</em></td><td>864</td><td>15–20</td></tr><tr><td><em>Pan-STARRS</em></td><td><em>i</em></td><td>1055</td><td>20–30</td></tr><tr><td><em>WISHES</em></td><td><em>z</em></td><td>462</td><td>~ 4</td></tr></tbody></table>
<figure><img src="image_29.png" /><figcaption>**Fig. C.3.** Footprint of the Euclid observations selected for main SC8 production.</figcaption></figure>

<figure><img src="image_30.png" /><figcaption>**Fig. C.4.** Positions of the exposures and the number of layers for the CFIS *u* and *r* bands.</figcaption></figure>

<figure><img src="image_31.png" /><figcaption>**Fig. C.5.** Positions of the exposures and the number of layers for the JEDIS *g* band.</figcaption></figure>
<figure><img src="image_32.png" /><figcaption>**Fig. C.6.** Positions of the exposures and the number of layers for the Pan-STARRS *i* band.</figcaption></figure>

<figure><img src="image_33.png" /><figcaption>**Fig. C.8.** Positions of the exposures and the number of layers for the LSST *u* band. The number of exposures and layers for the *u* and *z* bands are roughly equal.</figcaption></figure>

<figure><img src="image_34.png" /><figcaption>**Fig. C.7.** Positions of the exposures and the number of layers for the WISHES *z* band.</figcaption></figure>
<figure><img src="image_35.png" /><figcaption>**Fig. C.9.** Positions of the exposures and the number of layers for the LSST *g* band. The number of exposures and layers in *g*, *r*, and *i* bands are also approximately the same.</figcaption></figure>

<figure><img src="image_36.png" /><figcaption>**Fig. C.10.** Observations and the number of layers in DES SC8 main survey. Exposures of different bands (*g*, *r*, *i*, and *z*) are at the same positions.</figcaption></figure>