diff --git a/db/queries/queries.sql b/db/queries/queries.sql
index 9ba4148..d18cd25 100644
--- a/db/queries/queries.sql
+++ b/db/queries/queries.sql
@@ -59,7 +59,8 @@ SELECT * FROM observers WHERE public_key = $1;
 SELECT * FROM observers WHERE id = $1;
 
 -- name: GetObserverBrokers :many
-SELECT broker_name FROM observer_brokers
+SELECT broker_name, last_seen, last_packet_at
+FROM observer_brokers
 WHERE observer_id = $1
 ORDER BY last_seen DESC;
 
diff --git a/db/sqlc/queries.sql.go b/db/sqlc/queries.sql.go
index 7d4046b..9015616 100644
--- a/db/sqlc/queries.sql.go
+++ b/db/sqlc/queries.sql.go
@@ -210,24 +210,31 @@ func (q *Queries) GetNodeByPubkey(ctx context.Context, publicKey []byte) (Node,
 }
 
 const getObserverBrokers = `-- name: GetObserverBrokers :many
-SELECT broker_name FROM observer_brokers
+SELECT broker_name, last_seen, last_packet_at
+FROM observer_brokers
 WHERE observer_id = $1
 ORDER BY last_seen DESC
 `
 
-func (q *Queries) GetObserverBrokers(ctx context.Context, observerID uuid.UUID) ([]string, error) {
+type GetObserverBrokersRow struct {
+	BrokerName   string             `json:"broker_name"`
+	LastSeen     pgtype.Timestamptz `json:"last_seen"`
+	LastPacketAt pgtype.Timestamptz `json:"last_packet_at"`
+}
+
+func (q *Queries) GetObserverBrokers(ctx context.Context, observerID uuid.UUID) ([]GetObserverBrokersRow, error) {
 	rows, err := q.db.Query(ctx, getObserverBrokers, observerID)
 	if err != nil {
 		return nil, err
 	}
 	defer rows.Close()
-	items := []string{}
+	items := []GetObserverBrokersRow{}
 	for rows.Next() {
-		var broker_name string
-		if err := rows.Scan(&broker_name); err != nil {
+		var i GetObserverBrokersRow
+		if err := rows.Scan(&i.BrokerName, &i.LastSeen, &i.LastPacketAt); err != nil {
 			return nil, err
 		}
-		items = append(items, broker_name)
+		items = append(items, i)
 	}
 	if err := rows.Err(); err != nil {
 		return nil, err
diff --git a/db/store.go b/db/store.go
index bdb0d0e..93fc18c 100644
--- a/db/store.go
+++ b/db/store.go
@@ -536,7 +536,7 @@ func (s *Store) GetObserver(ctx context.Context, observerID uuid.UUID) (*api.Obs
 	if err != nil {
 		return nil, err
 	}
-	brokers, err := s.q.GetObserverBrokers(ctx, observerID)
+	brokerRows, err := s.q.GetObserverBrokers(ctx, observerID)
 	if err != nil {
 		return nil, err
 	}
@@ -562,8 +562,20 @@ func (s *Store) GetObserver(ctx context.Context, observerID uuid.UUID) (*api.Obs
 		FirstSeen:        obs.FirstSeen.Time.UnixMilli(),
 		LastSeen:         obs.LastSeen.Time.UnixMilli(),
 		ObservationCount: *obs.ObservationCount,
-		Brokers:          brokers,
 	}
+	brokers := make([]api.ObserverBroker, 0, len(brokerRows))
+	for _, v := range brokerRows {
+		var lastPacketAt int64
+		if v.LastPacketAt.Valid {
+			lastPacketAt = v.LastPacketAt.Time.UnixMilli()
+		}
+		brokers = append(brokers, api.ObserverBroker{
+			Name:         v.BrokerName,
+			LastPacketAt: lastPacketAt,
+			LastSeenAt:   v.LastSeen.Time.UnixMilli(),
+		})
+	}
+	observer.Brokers = brokers
 	if obs.LastStatusAt.Valid && time.Since(obs.LastStatusAt.Time) < 5*time.Minute {
 		observer.Status = "online"
 	}
diff --git a/internal/api/reader.go b/internal/api/reader.go
index 783ef03..424fdc3 100644
--- a/internal/api/reader.go
+++ b/internal/api/reader.go
@@ -18,27 +18,36 @@ type ObserverSummary struct {
 	Status       string    `json:"status"`                 // "online" or "offline" derived from last_status_at
 }
 
+// ObserverBroker represents a single MQTT broker an observer has been seen on,
+// including timestamps for diagnosing partial outages — e.g. distinguishing
+// "observer is down" from "one broker stopped delivering for this observer".
+type ObserverBroker struct {
+	Name         string `json:"name"`         // broker name e.g. "mqtt1"
+	LastSeenAt   int64  `json:"lastSeenAt"`   // epoch ms, last time observer was seen on this broker
+	LastPacketAt int64  `json:"lastPacketAt"` // epoch ms, last packet received via this broker; 0 if none
+}
+
 // Observer is the full observer representation including radio config,
 // telemetry, broker memberships and raw status metadata.
 type Observer struct {
 	ObserverSummary
-	PublicKey        string          `json:"publicKey"` // hex-encoded public key
-	SoftwareVersion  *string         `json:"softwareVersion,omitempty"`
-	HardwareModel    *string         `json:"hardwareModel,omitempty"`
-	FirmwareVersion  *string         `json:"firmwareVersion,omitempty"`
-	FirmwareBuild    *string         `json:"firmwareBuild,omitempty"`
-	RadioFreqMHz     *float32        `json:"radioFreqMhz,omitempty"` // MHz e.g. 910.525
-	RadioSF          *int16          `json:"radioSf,omitempty"`      // LoRa spreading factor
-	RadioBWKHz       *float32        `json:"radioBwKhz,omitempty"`   // bandwidth in kHz
-	RadioCR          *int16          `json:"radioCr,omitempty"`      // coding rate denominator
-	BatteryLevel     *float32        `json:"batteryLevel,omitempty"` // volts, nil if mains powered
-	UptimeSeconds    *int64          `json:"uptimeSeconds,omitempty"`
-	StatusMetadata   json.RawMessage `json:"statusMetadata,omitempty"` // raw /status JSON payload
-	LastStatusAt     *int64          `json:"lastStatusAt,omitempty"`   // epoch ms
-	FirstSeen        int64           `json:"firstSeen"`                // epoch ms
-	LastSeen         int64           `json:"lastSeen"`                 // epoch ms
-	ObservationCount int64           `json:"observationCount"`
-	Brokers          []string        `json:"brokers"` // broker names this observer has been seen on
+	PublicKey        string           `json:"publicKey"` // hex-encoded public key
+	SoftwareVersion  *string          `json:"softwareVersion,omitempty"`
+	HardwareModel    *string          `json:"hardwareModel,omitempty"`
+	FirmwareVersion  *string          `json:"firmwareVersion,omitempty"`
+	FirmwareBuild    *string          `json:"firmwareBuild,omitempty"`
+	RadioFreqMHz     *float32         `json:"radioFreqMhz,omitempty"` // MHz e.g. 910.525
+	RadioSF          *int16           `json:"radioSf,omitempty"`      // LoRa spreading factor
+	RadioBWKHz       *float32         `json:"radioBwKhz,omitempty"`   // bandwidth in kHz
+	RadioCR          *int16           `json:"radioCr,omitempty"`      // coding rate denominator
+	BatteryLevel     *float32         `json:"batteryLevel,omitempty"` // volts, nil if mains powered
+	UptimeSeconds    *int64           `json:"uptimeSeconds,omitempty"`
+	StatusMetadata   json.RawMessage  `json:"statusMetadata,omitempty"` // raw /status JSON payload
+	LastStatusAt     *int64           `json:"lastStatusAt,omitempty"`   // epoch ms
+	FirstSeen        int64            `json:"firstSeen"`                // epoch ms
+	LastSeen         int64            `json:"lastSeen"`                 // epoch ms
+	ObservationCount int64            `json:"observationCount"`
+	Brokers          []ObserverBroker `json:"brokers"` // broker names this observer has been seen on
 }
 
 // ChannelMessage represents a single decrypted channel message.