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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.

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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.

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

10925 results found.

  1. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  2. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  3. EP260628a: EP-FXT follow-up observation
  4. EP260628a: EP-WXT detection of a fast X-ray transient
  5. GRB 260619A: SVOM/ECLAIRs refined analysis
  6. EP260623a: Optical follow-up observations with Kinder
  7. EP260623a: SVOM/VT optical observations
  8. EP260623a: OSIRIS+/GTC redshift z = 0.703
  9. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  10. GRB 260619A: SVOM/VT optical counterpart confirmation
  11. GRB 260618B: SVOM/VT optical candidate
  12. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  13. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  14. GRB 260618B: Fermi-LAT detection
  15. GRB 260610B: AbAO optical observations
  16. GRB 260506B: cubesat Avion detection
  17. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  18. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  19. GRB 260429A: cubesat Avion detection
  20. GRB260616C: MAXI/GSC detection
  21. GRB 260616A: Fermi-LAT detection
  22. GRB 260610B: Terskol optical observations
  23. GRB 260614B: SVOM/VT optical afterglow confirmation
  24. GRB 260610B / AT2026owq: GRANDMA optical observations
  25. GRB 260610B / AT2026owq: further SAO RAS optical observations
  26. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  27. GRB 260610B / AT2026owq: SVOM/VT optical observations
  28. GRB 260610B: IAC-80 Optical observations
  29. GRB 260610B / AT2026owq: SAO RAS optical observations
  30. GRB 260610B / AT2026owq: Early ATLAS observations
  31. EP260610b: SVOM/VT optical confirmation with blue color
  32. EP260610b: Gemini North optical counterpart candidate
  33. EP260610a: SVOM/VT optical upper limits
  34. IPN triangulation of GRB 260601A (short/hard)
  35. IPN triangulation of GRB 260601B / EP260601a
  36. GRB 260604C: SVOM/ECLAIRs refined analysis
  37. GRB 260604C: further SAO RAS optical observations
  38. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  39. GRB 260604C: SVOM/C-GFT upper limit
  40. GRB 260604C: GRANDMA further observations
  41. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  42. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  43. GRB 260607B: Fermi-LAT detection
  44. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  45. GRB 260604C: SAO RAS optical observations
  46. GRB 260604C: GRANDMA observations
  47. GRB260603A: SVOM/ECLAIRs refined analysis
  48. GRB 260604C: SVOM detection of a long burst
  49. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  50. GRB 260603A: NOT optical observations
  51. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  52. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  53. EP260602d: Optical Upper limits with kinder observations
  54. EP260602b: Liverpool Telescope and LCO observations
  55. EP260602a: GTC and Liverpool Telescope optical observations
  56. GRB 260601B / EP260601a: Mondy optical upper limit
  57. GRB 260603A: SVOM/VT optical observations
  58. EP260602a: SVOM/VT optical candidate
  59. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  60. EP260602a: Optical upper limits with Kinder observations
  61. GRB 260601B/EP260601a: SVOM/VT optical observations
  62. AT2026nik: EP-FXT X-ray counterpart
  63. GRB 260531A: MAXI/GSC detection
  64. IPN triangulation of GRB 260527A / EP260527a
  65. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  66. GRB 260529A: GOTO tentative optical afterglow candidate
  67. EP260526a: SVOM/VT optical upper limits
  68. EP260527a / GRB 260527A: NOT optical observations
  69. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  70. EP260527a: SVOM/VT optical observation
  71. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  72. EP-WXT 01709266106: NOT optical upper limits
  73. GRB 260421B: radio detection with the VLA
  74. GRB 260509A: CrAO ZTSh optical upper limit
  75. GRB 260516D: GOTO optical counterpart detection
  76. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  77. GRB 260516D: SVOM/VT optical bright candidate
  78. GRB 260515A: CrAO ZTSh BVRI optical observations
  79. EP260514a: SVOM/VT optical candidate
  80. GRB 260515A: SVOM/VT optical observations
  81. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  82. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  83. GRB 260509A: SVOM/VT optical observations
  84. GRB 260511A: EP-FXT follow-up observation
  85. GRB 260511B: EP-FXT follow-up observation
  86. GRB 260511A: SVOM/VT optical observations
  87. GRB 260511B: SVOM/VT optical observations
  88. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  89. GRB 260510B: SVOM/ECLAIRs refined analysis
  90. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  91. GRB 260510C: SVOM/VT optical counterpart confirmation
  92. GRB 260510B: SVOM/VT optical upper limits
  93. GRB 260510C: SVOM/VT optical upper limits
  94. GRB 260510C: MAXI/GSC detection
  95. GRB 260510C: SVOM detection of a burst
  96. GRB 260510B: SVOM detection of a burst
  97. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  98. EP260507a: SVOM/VT optical observations
  99. EP260507a: Kinder optical counterpart candidate
  100. EP260507a: LCO optical counterpart

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