Mosaic to New Raster outputting No Data

[ElsaSartor]

Hi, I have tried to solve this issue through online research and looking through other questions online here. I am trying to create a mosaic raster from 11 bathymetry tiles that I have imported into ArcMap using ASCII to Raster. I have imported these 11 tiles as floating point rasters and they do not have any spatial reference. My instructor has said that we should only project a raster after completing all other steps to avoid too much change to the data. I need to mosaic these 11 tiles together into one raster and then clip this mosaicked output to the extent of a shapefile I have. All the final outputs will have to have 1000 m cell size an be projected into ETRS 1989 LCC and all be stored in the same geodatabase. I have tried mosaicking the tiles without and with defining a projection, inside and outside of a geodatabase but no matter what I do, the Mosaic to New Raster tool always outputs a raster with values ranging from -3.40282e+38 to 3.40282e+38 and this raster cannot be seen even though it appears in the catalog and in the table of contents. If anyone can provide some insight into this please let me know, I really can't figure out what the issue is. I am using ArcMap 10.7.1, I could not find a location called ArcMap to put this under and I couldn't post without putting it in a location so sorry it is in Arc Pro.

[DavidPike]

I would have thought the mosaic operation would require a spatial reference? That's a big indicator of the problem. Defining the spatial reference will not affect the data, it just let's the system know what it's looking at.

Use the define spatial reference tool first and calculate statistics. Check the tiles match up with other boundary data etc.

[ElsaSartor]

I gave this a try but I am still getting the same result. I used modelbuilder to convert the ASCII tiles to rasters. I used iterate files and specified the ASC extension in the ASCII to Raster tool. Could this possibly be the issue? I'm thinking I'll try this again without specifying a file extension since maybe the tool is not taking the file I want.

[DanPatterson_Retired]

Also, you large negative and positive values are interesting.  Can you examine what he nodata value is set to and whether it has a world file.  

ASCII to Raster—Conversion toolbox | ArcGIS Desktop  (applies to arcmap as well)

It would be prudent to examine the extents of all/some and what, if any nodata value is being applied..

I would also suggest *.tiff as a raster output file type rather than a gdb or esri raster.

[DavidPike]

I'd also trying loading them into arcmap then right click, data, export and save as .tif you can also supply a spatial ref

[ElsaSartor]

To update this question: I was making a mistake with one of my input settings (I was giving the output raster a different cell size) and this is what was causing the issue. Thank you everyone for your help!