Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

21952 results found.

  1. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  2. GRB 240501B: GRBAlpha detection
  3. GRB 240430A: GRBAlpha detection
  4. LIGO/Virgo/KAGRA S240422ed: Host redshifts of AT2024hfq, AT2024hfu, and AT2024hmo from DBSP
  5. GRB 240426A: VZLUSAT-2 detection
  6. GRB 240425A: VZLUSAT-2 detection
  7. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  8. GRB 240501B: AstroSat CZTI detection
  9. GRB 240408B: VZLUSAT-2 detection
  10. GRB 240407A: VZLUSAT-2 detection
  11. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  12. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  13. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  14. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  15. GRB 240425A: GRBAlpha detection
  16. Fermi-LAT gamma-ray observations of IceCube-240424A
  17. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  18. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  19. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  20. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  21. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  22. EP240426b: AST3-2 optical upper limit
  23. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  24. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  25. EP240426b: EP-WXT detection of a new fast X-ray transient
  26. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  27. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  28. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  29. EP240426a: YAHPT optical upper limit
  30. XMM-Newton observation of EP240426a
  31. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  32. GRB 240414A: NOEMA detection
  33. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  34. EP240426a: GMG optical upper limit
  35. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  36. LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
  37. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility contuinued observations of S240422ed and candidate analysis
  38. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  39. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  40. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  41. S240422ed: MeerLICHT/BlackGEM photometry on AT2024hfx and archival ZTF detection
  42. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  43. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  44. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  45. GRB 240422A: Glowbug gamma-ray detection
  46. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  47. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  48. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  49. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  50. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  51. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  52. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  53. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  54. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  55. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  56. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  57. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  58. GRB 240421B: GRBAlpha detection
  59. LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
  60. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  61. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  62. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  63. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  64. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  65. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  66. GRB 240418A: Swift-BAT refined analysis
  67. LXT240402A/GRB240402B: Chandra X-ray detection
  68. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  69. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  70. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  71. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  72. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  73. LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification
  74. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  75. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  76. GRB 240421A: Glowbug gamma-ray detection
  77. GRB 240414A: radio detection with the VLA
  78. Fermi-LAT gamma-ray observations of IceCube-240419A
  79. GRB 240414A: AMI-LA radio observations
  80. GRB 240414A: LBT optical detection
  81. GRB 240419B : MITSuME Akeno optical upper limits
  82. GRB 240421B: AstroSat CZTI detection
  83. GRB240421B: Zadko Observations
  84. GRB240421B: BOOTES-5/JGT optical upper limit
  85. GRB 240421B: J-band upper limits from WINTER
  86. GRB 240421B: Swift/UVOT Upper Limits
  87. GRB 240421B: Enhanced Swift-XRT position
  88. EP240417a: no counterpart detection by SOAR
  89. EP240420a: Xinglong decaying optical counterpart
  90. GRB 240421B: Swift detection of a burst
  91. EP240420a: Nanshan optical counterpart observations
  92. EP240420a: GWAC-F50A optical upper limit
  93. LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
  94. EP240420a: detection of fading X-ray emission with refined position by EP-FXT
  95. EP240420a: NOT optical counterpart candidate and potential host
  96. GRB240419A: Skynet Optical Afterglow Analysis
  97. GRB240418A - Candidate afterglow from NIRES
  98. GRB 240419B: Swift/UVOT Upper Limits
  99. EP240420a: EP-WXT detection of a fast X-ray transient
  100. GRB 240419A: Swift/UVOT Upper Limits

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov