Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

"N/A_MC161217_R1" does not adhere to advanced search syntax. Please refer to the documentation and try again.
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"

10902 results found.

  1. GRB 260917B: SVOM/VT optical observations
  2. GRB 260914A: Mondy and TShAO optical observations
  3. GRB 260914A: SVOM/ECLAIRs refined analysis
  4. GRB 260916A: MAXI/GSC detection
  5. GRB 260915A: SVOM/VT refined early optical upper limits
  6. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  7. GRB 260915A: SVOM/VT optical upper limits
  8. GRB 260915A: SVOM/VT optical upper limits from VHF data
  9. GRB 260915A: LCO optical upper limits
  10. GRB 260915A: SVOM detection of a burst
  11. GRB 260914A: SVOM/VT optical counterpart confirmation
  12. GRB 260914A: SVOM detection of a burst
  13. GRB 260818A: Continued ATCA observations
  14. GRB 260909A: CrAO and AbAO optical upper limits
  15. GRB 260909A: VLT optical and near-infrared upper limits
  16. GRB 260909A: EP-FXT follow-up observation
  17. GRB 260909A: SVOM/VT optical upper limits
  18. GRB 260909A: Mondy optical observations and afterglow candidate
  19. GRB 260909A: Xinglong 2.16m optical upper limit
  20. GRB 260903A: SAO RAS optical upper limit
  21. EP260903a: EP-FXT follow-up observation
  22. GRB 260903A: SAO RAS optical observations
  23. GRB 260903A: SVOM/VT optical candidate
  24. EP260901a: SVOM/VT optical upper limits
  25. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  26. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  27. GRB 260808B: SAO RAS observations of the optical rebrightening
  28. GRB 260822A: SVOM/VT optical upper limits
  29. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  30. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  31. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  32. EP260806a: SAO RAS multicolor optical observations
  33. EP260812a: AbAO optical upper limit
  34. EP260812b: Optical upper limit with Kinder
  35. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  36. EP260812b: SVOM/VT optical observation
  37. GRB 260809A: SAO RAS optical observations
  38. GRB 260808B: SAO RAS optical observations
  39. GRB 260808B: SVOM/VT optical re-brightening at day 3
  40. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  41. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  42. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  43. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  44. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  45. GRB 260809A: SVOM/VT optical counterpart
  46. GRB 260808B: SVOM/VT optical afterglow confirmation
  47. EP260806a: SVOM/VT optical observation
  48. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  49. EP260806a: OSIRIS+/GTC redshift z=0.089
  50. GRB 260715A: cubesat Avion detection
  51. GRB 260708A: cubesat Avion detection
  52. SN 2026stf / GRB 260708A: ATLAS forced photometry
  53. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  54. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  55. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  56. EP260727a: SAO RAS optical observations
  57. GRB 260727A: AbAO and SAO RAS optical observations
  58. GRB 260726A: SVOM/VT optical candidate
  59. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  60. GRB 260616A: cubesat Avion detection
  61. GRB 260602B: cubesat Avion detection
  62. GRB 260601A: cubesat Avion detection
  63. EP260723a: EP-FXT follow-up observation
  64. EP260723a: SVOM/VT optical observation
  65. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  66. GRB 260718A : GRANDMA and KNC upper limits
  67. GRB 260718A: SVOM/VT optical upper limits
  68. GRB 260718A: SVOM/VT optical upper limits from VHF data
  69. GRB 260618B: EP-FXT follow-up observation upper limit
  70. GRB 260714B: Fermi-LAT detection
  71. GRB 260619A: SVOM/VT continuous optical observations
  72. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  73. GRB260708B: MAXI/GSC detection
  74. GRB 260706A: SVOM/VT optical upper limits
  75. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  76. GRB 260705A: SVOM/ECLAIRs refined analysis
  77. GRB 260705A: SVOM detection of a burst
  78. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  79. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  80. EP260628a: EP-FXT follow-up observation
  81. EP260628a: EP-WXT detection of a fast X-ray transient
  82. GRB 260619A: SVOM/ECLAIRs refined analysis
  83. EP260623a: Optical follow-up observations with Kinder
  84. EP260623a: SVOM/VT optical observations
  85. EP260623a: OSIRIS+/GTC redshift z = 0.703
  86. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  87. GRB 260619A: SVOM/VT optical counterpart confirmation
  88. GRB 260618B: SVOM/VT optical candidate
  89. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  90. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  91. GRB 260618B: Fermi-LAT detection
  92. GRB 260610B: AbAO optical observations
  93. GRB 260506B: cubesat Avion detection
  94. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  95. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  96. GRB 260429A: cubesat Avion detection
  97. GRB260616C: MAXI/GSC detection
  98. GRB 260616A: Fermi-LAT detection
  99. GRB 260610B: Terskol optical observations
  100. GRB 260614B: SVOM/VT optical afterglow confirmation

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