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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_MC170405_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"

10919 results found.

  1. EP260623a: SVOM/VT optical observations
  2. EP260623a: OSIRIS+/GTC redshift z = 0.703
  3. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  4. GRB 260619A: SVOM/VT optical counterpart confirmation
  5. GRB 260618B: SVOM/VT optical candidate
  6. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  7. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  8. GRB 260618B: Fermi-LAT detection
  9. GRB 260610B: AbAO optical observations
  10. GRB 260506B: cubesat Avion detection
  11. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  12. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  13. GRB 260429A: cubesat Avion detection
  14. GRB260616C: MAXI/GSC detection
  15. GRB 260616A: Fermi-LAT detection
  16. GRB 260610B: Terskol optical observations
  17. GRB 260614B: SVOM/VT optical afterglow confirmation
  18. GRB 260610B / AT2026owq: GRANDMA optical observations
  19. GRB 260610B / AT2026owq: further SAO RAS optical observations
  20. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  21. GRB 260610B / AT2026owq: SVOM/VT optical observations
  22. GRB 260610B: IAC-80 Optical observations
  23. GRB 260610B / AT2026owq: SAO RAS optical observations
  24. GRB 260610B / AT2026owq: Early ATLAS observations
  25. EP260610b: SVOM/VT optical confirmation with blue color
  26. EP260610b: Gemini North optical counterpart candidate
  27. EP260610a: SVOM/VT optical upper limits
  28. IPN triangulation of GRB 260601A (short/hard)
  29. IPN triangulation of GRB 260601B / EP260601a
  30. GRB 260604C: SVOM/ECLAIRs refined analysis
  31. GRB 260604C: further SAO RAS optical observations
  32. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  33. GRB 260604C: SVOM/C-GFT upper limit
  34. GRB 260604C: GRANDMA further observations
  35. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  36. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  37. GRB 260607B: Fermi-LAT detection
  38. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  39. GRB 260604C: SAO RAS optical observations
  40. GRB 260604C: GRANDMA observations
  41. GRB260603A: SVOM/ECLAIRs refined analysis
  42. GRB 260604C: SVOM detection of a long burst
  43. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  44. GRB 260603A: NOT optical observations
  45. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  46. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  47. EP260602d: Optical Upper limits with kinder observations
  48. EP260602b: Liverpool Telescope and LCO observations
  49. EP260602a: GTC and Liverpool Telescope optical observations
  50. GRB 260601B / EP260601a: Mondy optical upper limit
  51. GRB 260603A: SVOM/VT optical observations
  52. EP260602a: SVOM/VT optical candidate
  53. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  54. EP260602a: Optical upper limits with Kinder observations
  55. GRB 260601B/EP260601a: SVOM/VT optical observations
  56. AT2026nik: EP-FXT X-ray counterpart
  57. GRB 260531A: MAXI/GSC detection
  58. IPN triangulation of GRB 260527A / EP260527a
  59. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  60. GRB 260529A: GOTO tentative optical afterglow candidate
  61. EP260526a: SVOM/VT optical upper limits
  62. EP260527a / GRB 260527A: NOT optical observations
  63. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  64. EP260527a: SVOM/VT optical observation
  65. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  66. EP-WXT 01709266106: NOT optical upper limits
  67. GRB 260421B: radio detection with the VLA
  68. GRB 260509A: CrAO ZTSh optical upper limit
  69. GRB 260516D: GOTO optical counterpart detection
  70. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  71. GRB 260516D: SVOM/VT optical bright candidate
  72. GRB 260515A: CrAO ZTSh BVRI optical observations
  73. EP260514a: SVOM/VT optical candidate
  74. GRB 260515A: SVOM/VT optical observations
  75. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  76. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  77. GRB 260509A: SVOM/VT optical observations
  78. GRB 260511A: EP-FXT follow-up observation
  79. GRB 260511B: EP-FXT follow-up observation
  80. GRB 260511A: SVOM/VT optical observations
  81. GRB 260511B: SVOM/VT optical observations
  82. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  83. GRB 260510B: SVOM/ECLAIRs refined analysis
  84. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  85. GRB 260510C: SVOM/VT optical counterpart confirmation
  86. GRB 260510B: SVOM/VT optical upper limits
  87. GRB 260510C: SVOM/VT optical upper limits
  88. GRB 260510C: MAXI/GSC detection
  89. GRB 260510C: SVOM detection of a burst
  90. GRB 260510B: SVOM detection of a burst
  91. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  92. EP260507a: SVOM/VT optical observations
  93. EP260507a: Kinder optical counterpart candidate
  94. EP260507a: LCO optical counterpart
  95. GRB 260504B: SVOM/ECLAIRs refined analysis
  96. GRB 260504B: SVOM/VT optical upper limits
  97. GRB 260421B: radio observation with the VLA
  98. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  99. EP260416a: Mondy and Terskol optical upper limits
  100. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory

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