download_tess_kepler: add forced python garbage collection

* the Tables can become huge, and therefor require a lot of RAM ->
* cleanup whenever we dont need a table anymore

download_tess_kepler.py

@@ -7,6 +7,7 @@ from astroquery.simbad import Simbad
 from enum import Enum
 import sqlite3
 import time
+import gc
 
 DEFAULT_DB = "stars.db"
 
@@ -297,24 +298,47 @@ simbad.add_votable_fields("distance")
 # TESS
 tessObs = Observations.query_criteria(obs_collection="TESS")
 tessProductList = getProductList(tessObs)
+del tessObs
+gc.collect()
 tessDataProducts = Observations.filter_products(tessProductList, productSubGroupDescription=["LC"], extension="fits")
+del tessProductList
+gc.collect()
 tessManifest = getManifest(tessDataProducts)
+del tessDataProducts
+gc.collect()
 insertManifestIntoDB(tessManifest)
+del tessManifest
+gc.collect()
 
 # Kepler
 keplerObs = Observations.query_criteria(obs_collection="Kepler")
 keplerProductList = getProductList(keplerObs)
+del keplerObs
+gc.collect()
 keplerDataProducts = Observations.filter_products(keplerProductList, productSubGroupDescription=["SLC"], extension="fits")
+del keplerProductList
+gc.collect()
 keplerManifest = getManifest(keplerDataProducts)
+del keplerDataProducts
+gc.collect()
 insertManifestIntoDB(keplerManifest)
+del keplerManifest
+gc.collect()
 
 # K2
 k2Obs = Observations.query_criteria(obs_collection="K2")
 k2ProductList = getProductList(k2Obs)
+del k2Obs
+gc.collect()
 k2DataProducts = Observations.filter_products(k2ProductList, productSubGroupDescription=["SLC"], extension="fits")
+del k2ProductList
+gc.collect()
 k2Manifest = getManifest(k2DataProducts)
+del k2DataProducts
+gc.collect()
 insertManifestIntoDB(k2Manifest)
-
+del k2Manifest
+gc.collect()